Temperature responsive systems

ABSTRACT

A shape memory material activated device of the present invention uses a shape memory material activator to create a path through a shell wall of the device. The path through the shell wall may release a substance contained in the shell or allow a substance to enter the shell. The path may be created by fracturing, puncturing, exploding, imploding, peeling, tearing, stretching, separating, debonding, abrading or otherwise opening the shell and, may be permanent or reversible. The substance may be released in one location while the device is stationary or along a path while it is traveling, self-powered by the shape memory material activator. In addition, the substance may be delivered to an object upon contact with its surface. The self powering abilities allow these devices to be used as substance delivery devices as well as actuators, transporters, and energy conversion systems with modular characteristics and growth potential. The devices may be armed, prior to the beginning of their service life, to be placed in a state of readiness to release their substances once the path is created. Prior to arming they may be maintained at any temperature, incapable of releasing their substances. The devices according to the present invention may be used as temperature sensors or warning devices, drug delivery devices, and the like.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of Ser. No. 10/549,705, filed Jun.23, 2006 now U.S. Pat. No. 7,445,616, which is a continuation-in-part ofapplication Ser. No. 09/815,643, entitled “Temperature ActivatedSystems”, filed on Mar. 23, 2001, and issued on Jan. 27, 2004 as U.S.Pat. No. 6,682,521. This application also claims priority toPCT/US2004/008338, filed Mar. 17, 2004, which claims priority to U.S.Provisional Patent Application Ser. Nos. 60/454,624, entitled “Arming ofThermally Activated Systems”, filed on Mar. 17, 2003; 60/479,481,entitled “Pro-Active Systems”, filed on Jun. 19, 2003; 60/489,428,entitled “Mobile Systems”, filed on Jul. 23, 2003; and 60/408,809,entitled “Conversion Systems”, filed on Oct. 2, 2003, all of which areincorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The invention relates to shape memory material activated devices, andmore particularly, the invention relates to shape memory materialactivated systems, such as, temperature sensors, drug delivery systems,self-powered devices, energy conversion systems, and the like, whichemploy a shape memory material activator for self-powering and to createa path through a shell.

BRIEF DESCRIPTION OF THE RELATED ART

Temperature warning devices are used as safety devices for products suchas pharmaceuticals, foods, and beverages that are subject to loss ofpotency or strength, chemical alteration or degradation, spoilage,poisoning, and taste or flavor alteration if they are exposed to hightemperature or thawed from a frozen condition. Typically, all productshave a restricted temperature range outside of which the product beginsto change. Many different types of warning devices exist which warn theconsumer if the product has reached or exceed its safe temperaturelimits. Examples of temperature warning devices are described in U.S.Pat. Nos. 5,735,607; 5,531,180; 5,460,117; 5,335,994; and 4,664,056.

Drug delivery devices, such as transdermal patches or implantable drugdelivery systems, are available for delivery of drugs to a patient.These drug delivery devices may be manually activated prior to use, suchas by the removal of a peelable liner on a transdermal patch. However,it would be desirable to provide on demand activation of a drug deliverydevice by use of a shape memory material activator.

It would also be desirable to provide a simple and reliable shape memoryactivated device for use in a variety of applications. Some of theseapplications may require release of a substance by a mobile, selfpowered device, mass delivery of a substance over large areas, andability to maintain the device at any temperature prior to its usage.

SUMMARY OF THE INVENTION

The present invention relates to the creation of a path through a shellwall with the aid of a shape memory material. The path through the shellwall may release a substance contained in the shell or allow a substanceto enter the shell. The path may be created while the shell isstationary or self-propelling. The substance may pass through the pathinstantaneously or over a temperature interval at a specific location oralong a course. The shape memory material may stay dormant, unable tocreate a path at any temperature, until arming takes place. The devicesaccording to the present invention may be used as substance deliverydevices, temperature sensors or warning devices, drug delivery devices,actuators, energy conversion systems and the like. The path creation isaccomplished by the shape memory material by several means such asfracturing, exploding, imploding, puncturing, peeling, tearing,shearing, rupturing, splitting, separating, abrading, squeezing,debonding etc. the shell. The method depends on the type of shell and onhow the shape memory material is utilized.

One aspect of the present invention relates to a temperature warningdevice, drug delivery device, or other device having a shell containinga first substance and an enclosure containing a second substance. Mixingof the substances is achieved by activation of a shape memory materialactivator. The shape memory material has been deformed in themartensitic state and its A_(s) to A_(f) temperature range includes thepredetermined temperature which is considered to be the maximum safetemperature of the product. For the temperature warning device, theenclosure is made of either a transparent or opaque material with atransparent window. Once the predetermined temperature has beenattained, the shape memory material recovers its shape and in theprocess applies a stress (tensile, compressive, shear, torsion, or acombination) that results in the creation of a path for the twosubstances to come in contact. The color of the enclosure fluid changesto indicate this effect and to provide the temperature warning throughthe transparent window.

In accordance with one aspect of the present invention, a temperaturesensor includes a shell containing a substance capable of providing anindication upon release from the shell, and a shape memory materialactivator for creating a path through the shell to release the substancefrom the shell in response to exposure to a temperature which is above amaximum or below a minimum safe temperature. The indication maystimulate one or more senses.

In accordance with an additional aspect of the present invention, ashape memory material activated device for opening a shell containing asubstance, the device includes a shell containing a substance, and ashape memory material activator configured to create a path through theshell once the shape memory material attains a predetermined temperatureor while it changes temperature within a predefined temperature range.The path creation may be repeatable with temperature cycling of theshape memory material. Multiple paths may be created in a plurality ofshells, simultaneously or sequentially with changing temperature of theshape memory material. A plurality of device may be grouped together toform a system to collectively produce a combined effect.

In accordance with a further aspect of the invention, a drug deliverysystem includes a shell containing a drug, and a shape memory materialactivator for creating a path to deliver the drug from the shell to apatient when a predetermined temperature of the shape memory materialactivator is achieved.

In accordance with yet a further aspect of the invention, aself-propelled substance delivery device includes a shape memorymaterial and a shell to deliver the substance along its path. Besidesdelivering a substance while traveling, the self propelled device iscapable of traveling to a specific location to create a path and deliverthe substance. In addition, the self-propelled device may be utilized asan actuator to perform tasks other than delivering a substance.

In accordance with yet another further aspect of the invention, anenergy conversion system comprises a plurality of shape memory materialactivators utilized to convert thermal energy to mechanical energy inthe form of linear or rotary motion. The mechanical energy may be usedto create a path through one or more shells or to actuate other devices.

In accordance with a further more aspect of the invention, a shapememory material activated device comprises a shape memory materialactivator configured to be armed through transformation form a dormantstate, incapable of responding to any temperature, to an active state ofreadiness, capable of responding to a predetermined temperature. Oncearmed, it may be utilized to create a path through a shell or to actuateother devices once the shape memory material attains a predeterminedtemperature.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in greater detail with reference tothe preferred embodiments illustrated in the accompanying drawings, inwhich like elements bear like reference numerals, and wherein:

FIG. 1 is a schematic side view of a shape memory material activateddevice with an internal shape memory material spring;

FIG. 2A is a schematic side view of the shape memory material activateddevice of FIG. 1 after activation;

FIG. 2B is a schematic side view of the shape memory activated device ofFIG. 1 after activation by stretching;

FIG. 3 is a schematic side view of a shape memory material activateddevice with an internal shape memory leaf spring;

FIG. 4 is a schematic side view of a shape memory material activateddevice with an internal non-shape material memory leaf spring and ashape memory material release member;

FIG. 5 is a perspective view of a shape memory material activated devicewith an exterior shape memory ring activator;

FIG. 6 is a schematic side view of a shape memory material activateddevice with an exterior shape memory spring activator;

FIG. 7 is a schematic side view of a shape memory material activateddevice in the form of a popping shell;

FIG. 8 is a schematic side view of a shape memory material activateddevice in the form of a shape memory material tube;

FIG. 9 is a schematic side view of the shape memory material activateddevice of FIG. 8 after activation;

FIG. 10 is a schematic side view of a shape memory material activateddevice with an interior shape memory material leaf spring;

FIG. 11 is a schematic side view of a shape memory material activateddevice with an exterior shape memory material leaf spring;

FIG. 12 is a schematic side view of a shape memory material activateddevice with an impact element;

FIG. 13 is a schematic side view of the shape memory material activateddevice of FIG. 12 after activation;

FIG. 14 is a schematic side view of a shape memory material activateddevice with an impact element and a shape memory material releasemechanism;

FIG. 15 is a schematic side view of the shape memory material activateddevice of FIG. 14 after activation;

FIG. 16 is a schematic side view of a shape memory material activateddevice with an external shape memory material activator;

FIG. 17 is a schematic side view of a three dimensional shape memorymaterial activated device;

FIG. 18 is a schematic side view of the three dimensional shape memorymaterial activated device of FIG. 17 after activation;

FIG. 19 is a schematic side view of a shape memory material activateddevice with an indirectly crushed shell;

FIG. 20 is a schematic side view of a shape memory material coil springcoupled with a bias coil spring;

FIG. 21 is a schematic side view of the shape memory material coilspring coupled with the bias coil spring of FIG. 20 after shaperecovery;

FIG. 22 is a schematic side view of a shape memory material leaf springcoupled with a bias leaf spring;

FIG. 23 is a schematic side view of the shape memory material leafspring coupled with the bias leaf spring of FIG. 22 after shaperecovery;

FIG. 24 is a schematic side view of a shape memory material activateddevice with an internal shape memory material spring and an internalbias spring;

FIG. 25 is a schematic side view of the shape memory material activateddevice of FIG. 24 after activation;

FIGS. 26, 27 and 28 are schematic side views of a shape memory materialactivated device with a folded wall shell, before during and afteractivation, respectively;

FIG. 29 is a schematic side view of a shape memory material activateddevice with a simultaneously unfolding wall shell;

FIG. 30 is a schematic side view of a shape memory material activateddevice with an accordion type shell;

FIG. 31 is a schematic side view of a shape memory material activateddevice with a bellows type pressurant;

FIG. 32 is a schematic side view of a shape memory material activateddevice with an abrading element;

FIG. 33 is a schematic side view of a shape memory material element bentin semi-circular segments of constant radii;

FIG. 34 is a schematic side view of a shape memory material element bentin segments of variable radii;

FIG. 35 is a schematic side view of a shape memory material activateddevice with a shape memory material activator bent in semi-circularsegments of constant radii;

FIG. 36 is a schematic side view of a shape memory material activateddevice with a shape memory material activator bent in segments ofvariable radii;

FIG. 37 is a schematic radial cross sectional view of a shape memorymaterial activated device with the shape memory material activatorintegrated into the wall of the shell;

FIGS. 38, 39 and 40 are schematic side views of a shape memory materialactivated device with a shrinking shell, before activation, afteractivation and after shrinking, respectively;

FIGS. 41, 42 and 43 are schematic side views of a shape memory materialactivated device with a growing shell, before activation, afteractivation and after growing, respectively;

FIG. 44 is a schematic side view of shape memory material activateddevice with a volume changing shell restrained with ratchet;

FIG. 45 is a schematic side view of a shape memory material activateddevice with a shell of two telescoping halves;

FIG. 46 is a schematic side view of a shape memory material activateddevice with volume changing shell and with the pressurization meansplaced outside of the shell;

FIG. 47 is a schematic side view of a shape memory material activateddevice with a controlled volume changing shell;

FIG. 48 is a schematic side view of a shape memory material activateddevice with a volume changing shell and two types of temperatureindicators;

FIGS. 49, 50 and 51 are schematic side views of a shape memory materialactivated device with a self-refilling shell, before activation, duringactivation and during refilling, respectively;

FIGS. 52, 53 and 54 are schematic side views of a shape memory materialactivated device with a self-refilling bellows type pressurant, beforeactivation, during activation and during refilling, respectively;

FIG. 55 is a schematic side views of a shape memory material activateddevice with a self-refilling shell connected to a hollow tube with axialfolds (shown in perspective);

FIG. 56 is a schematic side view of a shape memory material activatedtime dependent release system in an as installed position;

FIG. 57 is a schematic side view of the shape memory material activatedtime dependent release system of FIG. 56 in an open position;

FIG. 58 is a schematic side view of the shape memory material activatedtime dependent release system of FIG. 56 in an open position with asealer which has absorbed moisture;

FIG. 59 is a schematic side view of the shape memory material activatedtime dependent release system of FIG. 56 in a closed position after thesealer has absorbed moisture;

FIG. 60 is a schematic side view of the shape memory material activatedtime dependent release system of FIG. 56 containing a variablecomposition source;

FIG. 61 is a schematic side view of a shape memory material activatedtime dependent release system with a bias spring;

FIG. 62 is a schematic side view of a shape memory material activatedtime dependent release system with a central hole;

FIG. 63 is a schematic side view of a shape memory material activatedtime and temperature dependent release system in a partially openedposition;

FIG. 64 is a schematic side view of the shape memory material activatedtime and temperature dependent release system of FIG. 63 in a fullyopened position;

FIG. 65 is a schematic side view of an alternative shape memory materialactivated time and temperature dependent release system;

FIG. 66 is a schematic side view of a further alternative shape memorymaterial activated time and temperature dependent release system;

FIGS. 67 and 68 are schematic side views of a dome shaped, shape memorymaterial activated time and temperature dependent release system in aclosed and open position;

FIG. 69 is a schematic side view of a peelable shape memory materialactivated time dependent release system;

FIG. 70 is a schematic side view of a peelable shape memory materialactivated time dependent release system in the form of a transdermalpatch;

FIG. 71 is a schematic side view of a peelable shape memory materialactivated time dependent release system with multiple shells;

FIG. 72 is a schematic side view of an alternative peelable shape memorymaterial activated time dependent release system with multiple shells;

FIG. 73 is a schematic side view of a peelable shape memory materialactivated time dependent release system for delivery of a powderedsubstance;

FIGS. 74 and 75 are schematic side views of a peelable shape memorymaterial activated time dependent release system with a peelable linerpulled from two sides;

FIGS. 76 and 77 are schematic side views of a peelable shape memorymaterial activated time dependent release system with a rod shapedactivator;

FIG. 78 is a schematic side view of a peelable dual shell shape memorymaterial activated release system for releasing a substance outside of apredetermined temperature range;

FIG. 79 is a schematic side view of a shape memory material activateddevice with a membrane between the shell and the substance contained inthe shell;

FIG. 80 is a schematic side view of a shape memory material activatedrelease system in the form of an impact shell;

FIG. 81 is a schematic side view of another shape memory materialactivated release system in the form of an impact shell;

FIG. 82 is a schematic side view of a shape memory material activatedrelease system in the form of an integral impact shell;

FIG. 83 is a schematic side view of another shape memory materialactivated release system in the form of an integral impact shell;

FIG. 84 is a schematic side view of a release mechanism;

FIG. 84A is a cross sectional view taken along line A-A of FIG. 45;

FIGS. 84B, 84C, and 84D are schematic perspective views of the cupassembly in exploded, assembled, and released configurations,respectively;

FIG. 85 is a schematic side view of another release mechanism;

FIG. 85A is a cross sectional view taken along line A-A of FIG. 85;

FIGS. 86 and 87 are perspective views of a pull pin release mechanism;

FIG. 88 is a schematic view of a force limited release mechanism;

FIG. 89 is a schematic side view of a thermally powered device driven bya shape memory material activator;

FIGS. 90, 91 and 92 are schematic side views of a shape memory materialactivated transport device with the thermally powered device in theinitial position, with the forward end advanced, and with the aft endadvanced, respectively;

FIG. 93 is a schematic side view of a shape memory material activatedtransport device with the thermally powered device consisting of a shapememory material activator embedded in an elastomeric material;

FIG. 94 is a schematic axial cross section of a shape memory materialactivated transport device with the thermally powered device consistingof a shape memory material activator, trained in a two way shape memoryeffect;

FIG. 95 is a schematic side view of a thermally powered device travelingon a single internal track;

FIG. 96 is a schematic side view of a shape memory material activatedcircular transport device;

FIG. 97 is a schematic side view of shape memory material and biassprings housed in telescoping tubes;

FIGS. 98, 99 and 100 are schematic side views of a shape memory materialactivated transport device with the thermally powered device travelingon wheels in the initial position, with the forward end advanced, andwith the aft end advanced, respectively;

FIG. 101 is a schematic side view of a shape memory material activatedtransport device carrying a shell;

FIG. 102 is a schematic side view of a shape memory material activatedtransport device with shells located along the tracks;

FIG. 103 is a schematic side view of a thermally powered device with apointed nose;

FIGS. 104, 105 and 106 are schematic side views of a shape memorymaterial activated transport device carrying a time dependent releasedevice in the initial position with the release device closed, with theforward end advanced and the release device open, and with the aft endadvanced and the release device closed, respectively;

FIG. 107 is a schematic side view of a shape memory material activatedtransport device holding an element at the end of an extension arm;

FIG. 108 is a schematic side view of the device of FIG. 107 with ashell;

FIG. 109 is a schematic side view of an independent shape memorymaterial activated transport device with a tubular telescoping body;

FIG. 110 is a schematic side view of an independent shape memorymaterial activated transport device with a shape memory material body;

FIG. 111 is a schematic side view of an independent shape memorymaterial activated transport device with a multi-part body;

FIG. 112 is a schematic side view of a reversible fin-shape memorymaterial activated transport device;

FIG. 113 is a schematic side view of tubular expansion device with ashape memory material activated transport device having a collapsibletubular track;

FIG. 114 is a cross sectional view taken along line A-A of FIG. 113;

FIG. 115 is a schematic side view of a thermally powered devicetraveling on a single internal track with the variable length body madeof two telescoping halves;

FIG. 116 is a schematic side view of a shape memory material activatedcollapsible tubular expansion device in the collapsed position;

FIG. 116A is a schematic side view of the device in FIG. 116 in theexpanded position;

FIG. 117 is a schematic side view of a shape memory material activatedlateral expansion device with a linkage system;

FIG. 118 is a schematic side view of a shape memory material activatedlateral expansion device with a shell containing a substance;

FIG. 119 is a schematic side view of a shape memory material activatedeccentric tubular expansion device;

FIGS. 120, 121 and 122 are schematic side views of a thermally driventrack device by a shape memory material activator with the thermallypowered device anchored at the forward end, before shape recovery, aftershape recovery, and after reverse shape recovery, respectively;

FIGS. 123, 124 and 125 are schematic side views of a thermally driventrack device by a shape memory material activator with the thermallypowered device anchored at the mid point, before shape recovery, aftershape recovery, and after reverse shape recovery, respectively;

FIGS. 126 and 127 are schematic side views of thermally driven trackdevice with multiple thermally powered devices activated by shape memorymaterial, in the contracted and expanded positions, respectively;

FIGS. 128, 129 and 130 are schematic side views of a thermally driventrack device with a diverging fin-thermally powered device activated bya shape memory material and anchored at one end, before shape recovery,after shape recovery, and after reverse shape recovery, respectively;

FIG. 131 is a schematic side view of a circular thermally driven trackdevice with a shape memory material activator;

FIG. 132 is a schematic side view of a thermally powered device with agear system;

FIG. 133 is a schematic side view of a circular thermally driven powerdevice with a belt transferring power to a wheel.

FIG. 134 is a schematic side view of two similar circular thermallydriven track devices connected with a belt;

FIG. 135 is a schematic side view of a shape memory material activatedextrusion type release device;

FIG. 136 is a schematic side view of a shape memory material activatedrolling type release device;

FIG. 137 is a schematic side view of a shape memory material activatedgrinding type release device;

FIG. 138 is a schematic side view of shape memory material activatedthermally driven track with a reel of peelable shells;

FIG. 139 is a schematic side view of shape memory material activatedsqueeze type release device with two thermally driven tracks and anaccordion type shell;

FIGS. 140 and 141 are schematic side views of a thermally driven trackrelease device with two thermally powered devices and a time dependentrelease device in the closed and open position, respectively;

FIG. 142 is a schematic side view of two counter-rotating circularthermally driven track devices connected with a belt and a leverattached to it;

FIG. 143 is a schematic side view of a planar power distribution energyconversion system;

FIG. 144 is a perspective view of a three dimensional powerconcentration energy conversion system;

FIGS. 145 and 146 are schematic side views of a self cooling thermallypowered device with two cooling reservoirs, in the contacted andexpanded positions, respectively;

FIG. 147 is a schematic side view of a self cooling thermally powereddevice without valves;

FIG. 148 is a schematic side view of a self cooling thermally powereddevice in the vertical orientation with a single cooling reservoir;

FIGS. 149, 150 and 151 are schematic side views of an arming device,armed by pushing two ends together, in the unarmed, armed, and pathcreation positions, respectively;

FIG. 152 is a schematic side view of an arming device, armed by pushingtwo ends together, containing multiple shells;

FIG. 153 is a schematic side view of an arming device, armed by pushingtwo ends together, containing multiple peelable shells;

FIG. 154 is a schematic side view of an arming device, armed by pushingtwo ends together, configured with a witness window;

FIGS. 155 and 156 are schematic side views of an arming device, armed bypulling two ends apart, in the unarmed and the path creation position,respectively;

FIG. 157 is a schematic side view of an arming device, armed byrotation, in the unarmed position;

FIGS. 158, 159 and 160 are schematic side views of an arming device,armed by pushing two ends together with centrally located grippingelements, in the unarmed, armed, and path creation positions,respectively;

FIGS. 161 and 162 are schematic side views of an arming device, armed byengaging the pull tab of a peelable shell, in the unarmed and pathcreation positions, respectively;

FIGS. 163 and 164 are schematic side views of an arming device thatreleases a force, in the armed and force release positions,respectively;

FIG. 165 is a schematic side view of an arming device that releases aforce utilizing a thermally driven track;

FIG. 166 is a schematic side view of an arming device, armed by rotatingtwo parts of the device about a pivot point, in the unarmed position;

FIGS. 167, 168 and 169 are schematic side views of an arming device,armed by pressing the shell in the device, in the unarmed, armed, andpath creation positions, respectively;

FIGS. 170, 171 and 172 are schematic side views of an arming device witha deformable shell, in the unarmed, armed, and path creation positions,respectively;

FIGS. 173, 174 and 175 are schematic side views of an arming device witha foldable shell, in the unarmed, armed, and path creation positions,respectively;

FIG. 176 is a schematic side view of a thermally powered device in theunarmed position;

FIGS. 177 and 178 are schematic side views of a thermally driven trackin the unarmed and armed positions, respectively;

FIGS. 179, 180 and 181 are schematic side views of an arming device(without a shell) with a bias spring, in the unarmed, armed, and pathcreation positions, respectively;

FIGS. 182, 183, 184 and 185 are schematic side views of an armingdevice, that releases a substance with the fall of the temperature, inthe unarmed, armed, pull tab engagement, and path creation positions,respectively;

FIGS. 186, 187, and 188 are schematic side views of a hydraulic armingdevice, in the unarmed, armed, and path creation positions,respectively;

FIG. 189 is a schematic side view of a pneumatically arming device;

FIG. 190 is a schematic side view of a magnetically arming device;

FIGS. 191, 192, 193, 194 and 195 are schematic side views of a doubleaction arming device, with a cylindrical hollow shell, the shape memorymaterial spring in the austenitic and martensitic shapes, the armeddevice, and the path creation positions, respectively;

FIGS. 196, 197, 198 and 199 are schematic side views of an armingdevice, with a peelable shell, in the unarmed, armed, fine tuning, andpath creation positions, respectively;

FIG. 200 is a typical shape memory material displacement vs temperaturegraph.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This document describes a series of inventions for devices whoseprincipal operation is to create a path through a shell in order torelease or admit one or more substances. The path is created with thedirect or indirect aid of a shape memory material. The shape memorymaterial acts as a sensor to detect the release temperature and activateor actuate the device to release the substance. The released substancemay be utilized alone or may be mixed with a surrounding substance orsubstances to produce a new substance or group of substances withdifferent properties for further utilization. Mixing can also take placeinside the shell between the contained and the admitted substances. Eachsubstance, contained or admitted in the shell or surrounding the shell,can be at any single or combined state of matter; solid, liquid, or gas,whether classifiable or differentiated as one or not. This includes liveorganisms such as microbes, plant seeds and the like. Further, thesubstances contained in the shell may be part of a system whose purposeis to control the release or admission of the substance. An examplewould be a matrix inside the shell that contains the substance to bereleased or that is ready to absorb the admitted substance. The shellmay contain additional means to manage the release rate. Such exampleswould be a gas bladder that keeps the contents under pressure andaccelerates their release upon creation of the path, or a permeablebarrier that controls the release or admission rates of the substances.The surrounding substance can be at any static or dynamic state such asstill, agitated or flowing. Examples would be a fluid reservoir insidewhich the shell is contained, an agitated chemical solution or flowingblood in a mammalian body.

The released substance may or may not be the same or at the same stateas the substance contained in the shell. Examples of this would besubstances that upon release sublime, melt or volatize. In the firstcase, the contained substance may be in the solid state but the releasedsubstance is in the gas state. In the second case, the containedsubstance may be in the solid state but the released substance may be inthe liquid state. In the third case, the contained substance may be inthe liquid state but the released substance may be in the gaseous state.The release rate can be instantaneous at a predetermined temperature,continuous (constant or variable), controlled or integrated over time,or over time and temperature. These systems are mechanical in nature.However, they are capable of becoming electromechanical as will be shownlater. Conversion to electromechanical operation enhances theperformance of the systems and adds further capabilities.

The ability to release and mix substances at a predetermined temperatureor temperature range imparts unique capabilities to these devices. Someof these capabilities are: (1) production a new color upon mixing of twosubstances; (2) direct or indirect absorption of a substance, externallyor internally, by a mammalian body; (3) automatic initiation of achemical reactions; (4) remote controlled mixing rate or concentrationadjustment of a chemical solution; (5) germination of seeds and spores;(6) odor generation; (7) grouping of devices to form massivemulti-component delivery systems. Utilization of these capabilities canresult in a multitude of new or enhanced applications such as: (1)temperature warning devices and specifically, temperature indicators andtime-temperature integrator indicators; (2) on demand drug deliverysystems; (3) color changing toys; (4) control of chemical reactions; (5)agricultural and forestry products; (6) fragrance devices; (7) foodflavoring and taste enhancers. In addition, multiple devices can beemployed as variable scale release systems for specific substances suchas drugs, odors, disinfectants, sterilizers, fumigants, battlefield andriot control chemicals and the like. These devices have far morecapabilities and potential applications than the ones mentioned herein.Four main applications, temperature indicators, on demand drug deliverysystems, odor generation systems, and variable scale release systemswill be used as the main examples during the description of theinvention. In a number of the examples cited in this document, referenceis made to two substances; one contained inside the shell and oneoutside. The purpose of these examples is to demonstrate the mainfeatures and function of the devices. As mentioned above, the devicesare capable of containing and releasing or admitting more than onesubstance. However, the embodiments illustrated for one type of systemare capable of use for any of the other types of systems describedherein.

This document describes additional concepts to improve the operation andutilization of these devices. Several concepts are presented to controland improve the temperature release of the individual devices. Toachieve this, multiple means are employed to control: (1) the beginningof the path creation process and (2) the force required to create thepath. In addition, several concepts are presented that offer a selectionof release temperatures for individual devices. In these concepts, thedevice remains inactive, in a dormant state, unable to create a paththrough the shell when exposed to any temperature environment. Byfollowing a simple single action arming process, the device can beplaced in an active state of readiness, after which time it would createa path through the shell once the shape memory material activatorattains a predetermined temperature. The ability to arm the deviceprovides a choice of placing it in an active state by either thesupplier prior to shipping or the user prior to the beginning of itsservice life.

The inventions described herein utilize shape memory material to act astemperature sensors and to either activate or actuate the device whenthe predetermined temperature has been attained. Most materials withreasonable shape recoveries and development of adequate stresses duringthe shape recovery process can be utilized for these devices. Presently,nickel-titanium and copper based alloys adequately meet these criteriaand therefore are considered good candidates for these designs. For thesake of consistency, the nickel-titanium class of shape memory alloysknown as Nitinol is assumed to be used throughout this document. Inaddition, throughout the description reference is made to a typicalshape memory material Displacement vs Temperature graph shown in FIG.200.

The inventions described in this document are not restricted to anyparticular size or fabrication method. They can be scaled up or downwithout losing their functionality. They can be fabricated by any methodor technique without any restriction or limitation to the type oftechnology utilized.

Temperature warning devices are generally used as safety devices forproducts such as pharmaceuticals, foods, and beverages that are subjectto loss of potency or strength, chemical alteration or degradation,spoilage, poisoning, and taste or flavor alteration if they are exposedto high temperature. Typically, all products have a restrictedtemperature range outside of which the product begins to change. Thetemperature warning devices described below warn the consumer if theproduct has reached or exceed its safe temperature limits. Although thedescription is primarily concentrated on the high end of the temperaturerange, these devices can also be used to provide low temperatureprotection or warnings. The warning provided may be by visual means of acolor change, olfactory means of odor generation, gustation means oftaste alteration, haptic means of physical touching modification, andauditory means of acoustic signal creation. The acoustic signal is mostuseful for implant applications as will be seen later. Besides thedevices that indicate exposure to a temperature, this invention alsoincludes designs utilizing the same principle of operation fortime-temperature integrator indicators.

The substance release devices, when enabled with frictional means, canbecome self-powered and travel with temperature cycling. They can travelon surfaces, certain media, and on guided tracks. In the process oftraveling they can release a substance along their path or at specificlocations. In addition, they can release the substance to an object uponcontact with its surface. Besides releasing a substance, they arecapable of performing additional tasks such as transporting a load orconverting thermal energy into mechanical energy. Types of loads thatthey can transport include detection, diagnostic and robotic equipmentfor medical applications. Energy conversion increases the capabilitiesof the substance release devices by extending the operationaltemperature release range and providing additional methods to create apath through the shell walls to release the substances.

In the concepts described herein, the path created by the shape memorymaterial activator may be temporary or permanent and the substance maybe released once or repeatedly with temperature cycling. Further, thesubstance can be released over time, once a predetermined temperaturehas been attained, or while the temperature is changing. Any shapememory material of any configuration that can produce work withtemperature change is capable of being used as an activator to create apath though a shell wall for substance release.

To standardize the nomenclature and avoid confusion due to multipleapplications of these devices, at times the shell contents, whether theyare dye, drug, solute, solvent, or any other substance, will be referredto as the “source”. Also, the same contents will be referred to as thesubstance within the shell to distinguish them from the substance whichwill be the contents of the enclosure surrounding the shell.

FIGS. 1 and 2A illustrate a shape memory material activated device 10including an inner shell 12, a shape memory material spring 14 withinthe inner shell, and an outer shell or reservoir 16 surrounding theinner shell. According to one embodiment, a first substance is containedwithin the inner shell 12 and a second substance is contained within thereservoir 16. Initially, the shape memory material is in its martensiticstate and has been deformed from its original memory shape to assume theform of a compressed spring, as shown in FIG. 1. Surrounding the shapememory material spring 14 is a first substance in either a solid or aliquid state. Both the shape memory material and the first substance areencapsulated in a moisture impervious material shell 12. During theshape recovery process the shape memory material spring 14 developssufficiently large stresses to overcome the resistance offered by theshell 12 or encapsulant and creates a path 20 through the shell wall, asshown in FIG. 2A.

For this to take place, a material of the shell 12 must be brittleenough to fracture with minimal plastic deformation. Fracturing allowsthe first substance from the interior of the shell 12 to be releasedand, optionally, be mixed/dissolved or otherwise combined with thesecond substance within the reservoir 16. The color change (if present)is preferably visible through a window of the reservoir and becomes awarning indication that the predetermined temperature has been exceeded.Alternatively, the visible indication may signal another event such asthe release of a drug. FIG. 2A shows the inner shell 12 as a capsulethat separates or fractures into two pieces upon shape recovery. In thistype of design, allowances must be made for any volume increase duringthe recovery process. This can be accomplished by techniques such asentrapment of gas in the enclosure or by fabricating the enclosure fromexpandable material.

FIG. 2B illustrates an alternative embodiment of a shell 12′ which hasbeen stretched by the shape memory material spring 14 to create multiplesmall openings or paths through the shell. The paths may be in the formof pores, tears, fissures, or the like that make the shell permeable orsemi-permeable to allow a substance to exit or enter the shell. If theopenings in the shell are microscopic in size, mixing takes place bydiffusion through the shell wall.

The term “shell” as used herein is intended to mean any container orenclosure which is capable of being fractured, opened, severed,stretched, abraded, or otherwise modified to allow a substance to enteror exit the shell. In certain cases where a substance is in the solidform and it its insoluble to its surroundings, there may be no separateshell. In these cases, release of the substance takes place by abrasionor fracturing of the substance to particles of a size releasable to thesurrounding environment. The same definition applies to cases where thesubstance may consist of agglomerated smaller shells.

A temperature at which the device 10 is activated and the mixing of thetwo substances begins lies between the “Austenitic start” (A_(s)) andthe “Austenitic finish” (A_(f)) temperatures of the shape memorymaterial, FIG. 200. By the time the A_(f) temperature is reached a pathhas been created through the shell 12 indicating that the shape memorymaterial has recovered its shape either partially or fully. The A_(s)and A_(f) temperatures are determined primarily by the chemicalcomposition of the material, its thermo-mechanical processing and theamount of deformation from its shape memory state. The temperature rangeof operation of the device is equal to the difference between A_(f) andA_(s). However, in reality, movement does take place between thetemperatures A₁ to A_(s) and A_(f) to A₂. To narrow the A₁ to A₂ range,sufficient tolerances are allowed between the shape memory material andthe inside surface of the shell for partial recovery to take place untiltemperature A_(x) is reached. At this temperature, the shape memorymaterial spring 14 is in full contact with the inside surface of theshell 12 and the shape recovery stresses begin to be applied to itsinside surface. Conversely, by minimizing the tolerances, recoverybegins at A_(s) and the path is created by the time temperature A_(x) isreached.

The shell in all the embodiments described herein contains the substanceor drug to be released. Once the predetermined temperature is reached, apath is created through the shell that allows the two substances to comeinto contact. The two substances can be at single or multiple states ofmatter; solid, liquid, or gas. Additionally, the substances can be liveorganisms, plant seeds and the like. However, in most of the examplescited herein the enclosure substance is preferably in the liquid stateand the shell substance is in either the solid or liquid state.Typically, the shell substance is a dye capable of changing theenclosure's color once the two come in contact.

The path creation through the shell is achieved by activation of theshape memory material activator which creates a path by fracturing,exploding, imploding, puncturing, peeling, tearing, rupturing,splitting, or otherwise opening the shell. The shape memory material hasbeen deformed in the martensitic state and its A_(s) to A_(f)temperature range includes the predetermined temperature, which isconsidered to be the maximum safe temperature of the product. Theenclosure is either transparent, or an opaque material with atransparent window. Once the predetermined temperature has been reached,the shape memory material recovers its shape and in the process appliesa stress (tensile, compressive, shear, torsion, or a combination) thatresults in the creation of a path for the two substances to come incontact. The color of the enclosure fluid changes to indicate thiseffect and to provide the temperature warning through the transparentenclosure or window. The path creation is accomplished by the shapememory material by several means such as: fracturing, exploding,imploding, puncturing, peeling, tearing, shearing, rupturing, splitting,separating, debonding delaminating, squeezing, extruding etc. the shell.The method depends on the type of shell and on how the shape memorymaterial is utilized.

For the temperature warning device of FIGS. 1, 2A and 2B and thosedescribed below, the reservoir 16 can be of any shape as long as it doesnot interfere with the shape recovery of the shape memory materialspring 12 and the path creation process. The reservoir 16 can be made ofeither rigid or flexible materials. Construction of flexible materialswill allow the enclosure to conform to different surfaces for bonding.In the case of the flexible enclosure 16, consideration must be given tothe fact that the ambient pressure is transferred to the shell 12 thoughthe second substance or fluid in the enclosure. The shell 12 must beable to withstand this pressure and the shape memory material must beable to overcome it. Although the embodiment of FIGS. 1, 2A and 2B hasbeen described as a temperature warning device, it may also be used as adrug delivery device or in other applications. For use of the device 10as a drug delivery system, the reservoir 16 has to conform topharmaceutical requirements

The actual shape of the deformed shape memory material in themartensitic state does not have to necessarily be in the form of aspring 14, as shown in FIGS. 1, 2A and 2B. Important factors to beconsidered include the displacement produced and the actual stressgenerated during the shape recovery process. These factors depend on thegeometry of the shape memory material, amount of deformation, chemicalcomposition of the material, thermo-mechanical processing and the forcesrestricting its recovery process.

The shape memory material can be of any shape as long as during recoveryit is able to (a) produce sufficient displacement to come in contactwith the inside surface of the shell, and (b) produce sufficient forceto create a path through the shell walls. Determining factors for theshape of the shape memory material are (a) the amount of displacementrequired and (b) the properties and sizes of both the shape memorymaterial and the shell material.

FIG. 3 illustrates an alternative embodiment of a shape memory materialactivated device 30 having another shape. The device 30 includes aninner shell 32, a shape memory material spring 34, and an outer shell orreservoir 36. The shape memory material spring 34 is in the form of aleaf spring, curved in an initial configuration of FIG. 3, whichstraightens when exposed to the predetermined temperature. Thestraightening of the shape memory material spring 34 fractures the shell32 and creates a single or multiple paths through the shell wall. Thedevice 30 of FIG. 3 illustrates another shape for both the shape memorymaterial spring 34 and the shell 32. The shell 32 is formed of a curvedtube shape that can be designed to minimize the volume it occupies.

If the substances contained within the shell 12, 32 and the reservoir16, 36, prior to mixing or after mixing, react with the shape memorymaterial to the point that either the function of the device or itseffectiveness are affected, the shape memory material must be insulatedfrom the substances. This is achieved by containing the shape memorymaterial in a non-reactant material. Alternatively, this may be achievedby placing the shape memory material outside of the shell and/orreservoir as in the embodiments of FIGS. 5, 6, 11, and 19 discussedbelow.

The shape of the shell 12, 32 depends primarily on the amount ofsubstance it has to contain and the shape and size of the shape memorymaterial. The shell can consist of one or multiple parts. Parts can beheld together by several methods including, but not limited to; (a)mechanical pressure such as applied by mechanical fasteners, (b)mechanical interlocking such as interference fitting and thermalfitting, (c) chemical and thermo-chemical such as adhesive bonding, heatsealing and thermal shrinking, (d) any type of welding or weld bondingsuch as solid state, fusion, ultrasonic, brazing or soldering. Materialselection for the shell depends on both intrinsic and extrinsic factors.Intrinsic factors are material properties that must be such as to allowthe shape memory material to create a path through the shell walls.Extrinsic factors are; the type of heating to be used to activate thedevice, i.e. ambient, resistive, etc. and the time required for thedevice to be activated once the surroundings have reached thepredetermined temperature. Again, the material (or materials if morethan one is used) must not react with the substances contained in theshell and the enclosure prior to mixing or after mixing to the degreethat the effectiveness of the device is compromised.

There are cases where it would be desirable to have the shell degradeover time. If no path has been created through the shell to release itscontents, release would be achieved by the degradation process itself.This may arise from the inability, in certain cases, to retrieve theshell once placed in an environment where the temperature does notchange appreciably to activate the shape memory material, create thepath, and release the substance. The shell can be made of any materialthat would degrade in the environment that it is placed in. Degradationimplies any process such as decay, deterioration, decomposition,disintegration, corrosion of the shell that would result in the releaseof its contents over time. It involves any combination of environmentfactors and shell material. Examples of such combinations are, but notlimited to: (a) Shells made of wood products such as paper placed in amoist environment. (b) Shells made of organic material that degrade inthe presence ultra violent radiation. (c) Shells made of material thathave a tendency to corrode in specific environments by initiating andpropagating a corrosion process. (d) Shells made of biodegradablematerial and placed in an environment that would induce biodegradation.Another way to degrade the shell would be a reaction with its owncontents. Even though in most cases this is not a desirable effect,there are cases where this might be desirable provided that thedegradation is a long term effect that does not interfere with theoperation and effectiveness of the device during its intended life span.Degradation, at either a rapid or a slow rate, assures the release ofthe substance, thereby avoiding any problems of having a device placedin a service environment and remaining inactive.

Instead of using a shape memory material to both activate the device andcreate a path through the shell walls, the shape memory material can beused for the activation process and a regular spring of non-shape memorymaterial or a superelastic material may be used to create the path whilethe shape memory material is used as a release mechanism. FIG. 4illustrates an alternative embodiment of a shape memory materialactivated device 40 having a shell 42, a non-shape memory materialspring element 44, an enclosure 46, and a shape memory material releasemechanism 48.

Materials considered useful for the non-shape memory spring element 44include those having spring properties, such as carbon or alloy steel,stainless steels, and beryllium-copper alloys. The spring element 44 isrestrained by the release mechanism 48 in a position containing storedmechanical. Examples of restrained positions include (a) compressed coilsprings, bent wires or strips (as shown in FIG. 4) and (b) torsionsprings.

The spring element 44 of FIG. 4 is held in the restrained position bythe shape memory material release mechanism 48 that has been deformed inthe martensitic state to form a hook or loop. Alternatively, otherrestraining methods requiring deformation by stretching or shrinkingrather than bending may be used. As the temperature rises above A_(s),the shape memory material release mechanism 48 recovers its originalstraight shape. At one point, the spring element 44 is able to overcomethe restraining force applied by the shape memory material releasemechanism 48 and releases itself, goes to its free state, and in doingso utilizes the stored mechanical energy to create a path by fracturing,cracking, puncturing, peeling, tearing, shearing, delaminating orotherwise forming a path through shell 42. During the path creationprocess, upon impact with the shell wall it produces an auditory signalthat can be utilized as verification of the spring release. Depending onthe shape memory material configuration, different restraining methodscan be used. FIG. 4 shows a hook type release shape memory materialrelease mechanism provided on a leaf spring. The hook type releasemechanism may also be used in a device with a coil type spring, such asthe device illustrated in FIGS. 1, 2A and 2B. A number of differentrelease devices, based on the same principle, are discussed later withrespect to FIGS. 84-88.

As illustrated in the embodiments of FIGS. 5, 6, 11, and 19, the sameeffect achieved by placing the shape memory material activator insidethe shell can also be achieved by placing it on the outside.

FIG. 5 illustrates a device 50 having a substantially cylindrical shell52 and a ring-shaped, shape memory material activator 54 surrounding theshell. During shape recovery, the ring shaped activator 54 compressesand crushes the shell 52. Also, other shell/shape memory materialconfigurations can be used for this embodiment and the cylindrical shelland ring shaped activator are merely one example.

FIG. 6 illustrates a device 60 having an hour glass shaped shell 62 anda spring shaped shape memory material activator 64. According to thisembodiment, during shape recovery, the activator 64 expands axially andfractures or otherwise creates a path through the shell 62 bystretching.

FIG. 7 illustrates a popping shell type shape memory material activateddevice 70. In this concept, the popping shell consists of a shape memorymaterial sheet 72 having a flat austenitic shape and a deformeddimple-like martensitic shape, as shown in FIG. 7. The substance to bereleased is placed in the dimple 74 of the sheet, sealed by a seal 76.During shape recovery, the material of the popping shell 72 tries tobecome flat and in the process a path is created, releasing thesubstance. The path is created either through the seal 76, or betweenshape memory material sheet 72 and the seal at the interface.

FIG. 8 illustrates an example of shape memory material tubular shell. Inthis concept, the shells incorporate shape memory material tubes thathave been deformed in the martensitic state. Upon transformation to theaustenitic state, these tubes recover their shapes and create a path byfracturing the end seals when returning to their memory shape. Thisconcept relies on both volume and shape changes to break the end sealsand minimizes the part count required to construct the shell.

FIG. 8 shows a bent shape memory material tube 80 which becomes straightupon shape recovery and in the process breaks the end seals 82 andreleases its contents. FIG. 9 shows the shape memory material tube 80after the seals 82 have been broken causing the substance contained inthe tube 80 to be released.

In an alternative embodiment, a shape memory material tube may beflattened in the martensitic state to have an oval or other non-circularcross section. The shape memory material tube, upon transformation tothe austenitic state, recovers a round cross section and breaks the endseals.

FIG. 10 illustrates an embodiment of a non-shape memory material tubularshell 90 with a shape memory material activator 92. This conceptutilizes the flexible non-shape memory material tube 90 forming a shellfor containing a substance. The shape memory material activator element92 located either inside (FIG. 10) or outside (FIG. 11) and attached tothe tube 90 such that during shape recovery the tube assumes a differentshape, i.e. bent to straight, and in the process breaks the end seals94. In the case of FIG. 11, where the shape memory material activatorelement 92 is placed on the outside of the tube 90, the shape memorymaterial activator element 92 is attached to the tube by bands 96 orother means.

FIGS. 12 and 13 illustrate an example of the use of shape memorymaterial activators for puncturing or crushing a shell. FIG. 12 shows ashape memory activated device 100 including a shell 102 arranged to bepunctured by a shape memory material activator 104 in the form of a coilspring. A cylinder 106 is used as a guide for the spring 104. The shapememory material activator 104 may be provided with a puncturing element108 if necessary, depending on the force provided by the shape memorymaterial activator and the strength of the shell 102.

FIGS. 14 and 15 illustrate the same concept of a shape memory materialactuated device 110 in which a shell 112 is punctured or crushed, exceptthat in the device 110, a regular (non-shape memory material) spring 114is held in compression with a shape memory material release element 116.In both cases the coil spring can be designed to either puncture theshell with a sharp pointed end or to crush it with a blunt end.

FIG. 16 illustrates a shape memory material activated device 120 whichcreates a path by twisting the shell. The device 120 includes a twistedshell 122 and two shape memory material elements 124 arranged on paddles126 attached to the shell. The shear stress generated by the two shapememory material elements 124 become sufficiently large during the shaperecovery process to create a path through the shell wall. The paddles126 can be either rigidly attached to the shell 122 or they can bepivoted and allowed to rotate in order to more efficiently transfer theforce generated by the shape memory material elements 124 to the shell.A top view of the device 120 is similar to the release mechanism shownin FIG. 84A.

FIGS. 17 and 18 illustrate a three dimensional shape memory materialactivated device 130. This concept is utilized to detect bulktemperatures, i.e. other than surface temperatures, and it is primarilyapplicable to temperature warning devices. The detection mechanism 132,which can be any of the mechanisms described herein, is placed at thebottom of a tube, 134 and a transparent window 136 is attached to thetop end of the tube. In this case, the detection mechanism illustratedis similar to the device illustrated in FIGS. 1, 2A and 2B. The tube 134constitutes a part of the enclosure. The tube 134 can be made offlexible material to accommodate areas inaccessible via line of sight.Once the warning temperature is reached, the shell fractures and a colorchange is produced which is visible through the clear window 136.Typically, the agitation generated by the fracture of the shell will besufficient to aid the mixing process. However, in the case of long andnarrow tubes 134 this may not be sufficient. In these cases, any gascontained in the shell will form one or more bubbles that will rise tothe window 136 and in the process produce further agitation therebyenhancing the mixing process. In the cases where no gas is contained inthe shell, gas can be incorporated in the dye if the dye is made oflightly compacted powder. The gas agitation method will work best if thedevice is vertically oriented.

FIG. 19 illustrates a shape memory material activated device 140 with anindirectly crushed shell 142. The device 140 includes the shell 142, ashape memory material activator 144 in the shape of and external spring,and an enclosure 146. The methods presented so far for creating a paththrough the shell walls are based on direct application of force on theshell, either from the inside or the outside of the shell. Most of thesemethods can also be used to apply the force to enclosure 146 and have ittransmitted to the shell 142 via the fluid of the enclosure 146(provided that the enclosure contains a fluid), as shown in FIG. 19.This concept is viable when the following two basic conditions areapplied: the enclosure does not fracture prior to the shell and, theshell and its contents are not either incompressible or insufficientlycompressible to fracture.

A good example of this concept is the case where the contents of theshell 142 are in solid, loosely packed powder form. This system offersthe advantage of reduced cost by having one common enclosure 146 andshell 142 for use at all temperatures and having the shape memorymaterial activator 144, with different A_(s) temperatures, installed atthe end of the assembly process or prior to the application. Also, itavoids the storage and transportation costs associated with maintainingthe devices at a temperature lower that the activation temperature priorto application.

According to one alternative embodiment of the inventions describedherein, the invention may employ devices similar to the devicesdescribed herein except that the shape memory material activatoractivates at a minimum temperature. In this embodiment, the shape memorymaterial activator has been trained to achieve a two way shape memoryeffect. The purpose of this reverse system is to detect minimumtemperatures and release a substance from a shell when such a minimumtemperature has been exceeded. To do so, a shape memory material isselected whose martensitic transformation range M_(s) to M_(f) includesthe minimum release temperature. Initially, the shape memory material istrained to achieve a two way shape memory effect with the austenitic(recovered) shape being the installation shape and the martensitic(original) shape being the one undertaken once the material is exposedto the predetermined temperature. At this temperature, the shape memorymaterial creates a path through the shell walls and releases thesubstance from the shell. For single release type devices, the shapememory material is required to exhibit the two way shape memory effectonly once, when the service temperature drops below the predeterminedtemperature. In essence, the shape memory material in the reverse designoperates in the reverse temperature cycle. Actuation takes place duringcooling from austenite to martensite, whereas in high temperatureactivation case actuation takes place during heating, from martensite toaustenite. The same features used in all of the other designs describedherein can also used with the reverse system. The two way shape memoryeffect, besides being utilized in shell containing devices, can also beincorporated in embodiments presented elsewhere in this specification tobe actuated upon cooling below the M_(s) temperature.

According to another embodiment of path creation during cooling, theshape memory material activator that is trained in a two way shapememory effect is utilized to restrain a non-shape memory materialspring. The non-shape memory material spring is deformed elastically andcontains stored mechanical energy. During cooling below M_(s) the shapememory material begins to undergo reverse shape recovery and releasesthe restrained spring that in turn unleashes the mechanical energy tocreate a path by an impact force.

A path can also be created when the temperature of the shape memorymaterial element decreases below a predetermined minimum value withinthe M_(s) and M_(f) range without the sole utilization of the two wayshape memory effect described above. This is achieved with theincorporation of a bias spring. A bias spring is a non-shape memorymaterial spring that is capable of storing mechanical energy whendeformed elastically by the shape memory material undergoing shaperecovery. Initially, the shape memory material spring is deformed in themartensitic state, and then the two springs are assembled together suchthat the bias spring remains in its free state. Once assembled, they areexposed to a temperature above A_(f) and are maintained at or above thistemperature. During the shape recovery process from A_(s) to aboveA_(f), the shape memory material deforms the bias spring elastically.This becomes the installation state, and activation of the device doesnot begin until the temperature of the shape memory material begins todecrease below M_(s). As the temperature decreases below M_(s), theresistance offered by the shape memory material spring begins todecrease and it is overtaken by the force exerted by the bias spring. Asthe temperature continues to decrease, the bias spring is forcing theshape memory material spring back to its martensitic state whileproducing a displacement. Once the production of the displacement isrestricted by the wall of the shell, a force is generated and, when itreaches a sufficient magnitude, creates a path through the shell wall torelease the substance. This force can also be used in alternativedesigns with enhanced capabilities such as to create a path though ashell wall during cooling (M_(s) to M_(f)) and close it during heating(A_(s) to A_(f)) or vice versa, and repeat this operation withtemperature cycling. Further, this type of force can be used to create apath through the wall of all the shells described herein, including thepeeling of the wall of a shell.

For background information, FIGS. 20 to 24 illustrate mechanismscomprised of shape memory material springs coupled with bias springs.FIG. 20 illustrates an activation mechanism 150 comprising two coilsprings, a shape memory material spring 152 and a bias spring 154,positioned inside each other. When a compressive force is required tocreate a path, the shape memory material spring 152 is deformed bytension in the martensitic state and is assembled with the bias spring154. During the shape recovery process, as the temperature increasesfrom A_(s) to A_(f), the length of the shape memory material springdecreases and places the bias spring in compression. FIG. 21 illustratesthe decreased length of both springs; shape memory material 152 and abias 154 springs after shape recovery. When the temperature drops belowM_(s), the shape memory material spring begins to undergo reverse shaperecovery, weakens, and when its resistance drops below the magnitude ofthe force offered by the bias spring, a displacement is produced whichwhen constrained produces a compressive force. If there is noconstraint, during reverse recovery the mechanism returns to itsmartensitic length, illustrated in FIG. 20, once the temperature of theshape memory material spring reaches M_(f). This compressive force canbe utilized to create the path through a shell wall. The nature of thisreverse recovery force can be changed from compressive to tensile,simply by deforming the shape memory material spring in compression inthe martensitic state prior to coupling it with the bias spring. Theadvantage of utilizing a bias spring is that path can be created throughthe shell wall with either a tensile or a compressive force to releaseor admit a substance during cooling of the shape memory material.Coupling of shape memory material and bias spring is not restricted toparallel positioning only. They can be coupled in series such that ifrestrained at the two ends, a displacement is produced with temperaturechange at the point of contact between the two springs. In addition,various types of springs can be combined to create a path through thewall of a shell with falling temperature of the shape memory materialspring.

FIG. 22 illustrates an activation mechanism 160 comprising two leafsprings, a shape memory material spring 162 and a bias spring 164. Whena leaf spring is required to create the path by producing a force duringa shape change from straight to curved, the above process is repeatedexcept that the shape memory material spring 162 is deformed by bendingin the martensitic state. Then, it is mated with the bias 164 springwhich is permanently bent to the same radius, and the two are heated toa temperature above A_(f). During the shape recovery process, the shapememory material spring 162 forces the bias spring 164 to deformelastically and to assume a straight shape by the time the A_(f)temperature is attained, FIG. 23. During cooling, the process isreversed and, if the mechanism is restrained form assuming themartensitic shape, a constrained force is produced. This force can beutilized to create a path through the wall of a shell to release or toadmit a substance. The concept of incorporating a bias spring to createa path through the wall of a shell can be used with any type of shapememory material and bias springs.

FIG. 24 illustrates a shape memory material activated device 170comprising an inner shell 172, a shape memory material spring 174 and abias spring 176 within the inner shell 172, and an outer shell orreservoir 178 surrounding the inner shell. This device is similar todevice 10, with the exception that the path creation takes place duringcooling. When the temperature of the shape memory material spring beginsto fall below M_(s), the reverse recovery force, generated from thecoupling of the shape memory material spring 174 and the bias spring176, creates a path through the wall of the shell 172, illustrated inFIG. 25, to release the substance contained in the shell 172 to thereservoir 176. The same concept of utilizing coil springs can beutilized to create a path in more shells such as those describedpreviously in devices 10, 60 and 100.

Besides creating a path directly through the wall of a shell, couplingof leaf springs can also be used to create the path indirectly byreleasing an elastically deformed non-shape memory material springcontaining stored mechanical energy to create a path through the shellwall. This is the same concept as the one illustrated in FIGS. 4, 14 and15, with the exception that the restraining element is a coupling of ashape memory material spring and a bias spring, and path creation takesplace when the shape memory material spring is cooled bellow M_(s).Incorporation of a bias springs is not restricted to substance releasedevices only, it can be utilized in any design requiring actuation withthe fall of temperature of the shape memory material spring.

FIGS. 26, 29 and 30 illustrate alternative embodiments of a shape memorymaterial activated device in which the shape memory material activatordoes not create a path through the wall of the shell directly. Instead,the path is created by utilizing the shape recovery force to create anew shell surface while the shape memory material activator undergoes atemperature change. The new surface contains pre-existing paths for theshell to release or admit a substance.

FIG. 26 illustrates a shape memory material activated device 180comprising a shell 182 with part of its wall made up of a folded wall184 and a shape memory material spring 186 within the shell.Alternatively, the shape memory material spring 186 can be locatedoutside the shell. During the shape recovery process the folded part ofthe shell wall 184 unfolds to expose new shell surface that containspreexisting paths for the substance to enter or exit the shell.Unfolding can take place by two different methods that depend on thetype of shell used. The first one comprises of a sequential unfolding ofthe folded wall while the second one comprises a simultaneous unfolding.

In the first method, unfolding takes place sequentially as the shapememory material spring undergoes shape recovery such that eachindividual fold opens up after the previous fold has opened up. This isillustrated in FIGS. 27 and 28. FIG. 27 shows a partial unfolding of theshell wall 184 while FIG. 28 shows the final unfolding of the shell wall184 after the shape recovery of the shape memory material 186 iscompleted. This concept has the advantage of creating a path by exposingdifferent areas of the shell wall as the temperature increases fromA_(s) to A_(f). By designing each fold with different degree ofpermeability, size and number of pores or openings, the release oradmission rate of the substance can vary with temperature but remainscontrolled throughout the transformation range. This type of shellrequires that successive folds be held together with increasing contactforces such that increasing shape recovery forces are required to openthem up sequentially. Different construction methods can be employed toachieve the sequential unfolding. Such methods may include the use ofincreased strength adhesives to bond successive folds or mechanicalinterlocking of successive folds with increasing contact stresses

FIG. 29 illustrates an example of a shape memory material activateddevice 190 comprising a shell 192 with part of its wall made up of afolded wall 194 and a shape memory material spring 196. During the shaperecovery process, the shape memory material spring 196 expands and allfolds of the folded wall 194 unfold simultaneously until completion ofthe shape recovery process. The path is created by opening up all folds,whose surfaces contain preexisting paths, at the same ratesimultaneously in an accordion fashion. This path creation methodprovides a smoother rate of release or admittance of the substance withchanging temperature while the first method provides more of a stepwiserate increase.

Depending on the particular application, one shell type might bepreferred over the other. For example, in some temperature warningsystems the accordion type may be preferred in order to provide a morelinear indication of time exposure with changing temperature. On theother hand, the sequential method may be preferred in order to provide asubstantially increased release with temperature that would acceleratethe coloring of the surrounding substance. While in both shell types,the path creation process is the same and both produce the same effectat constant temperature, they differ with respect to the release oradmittance rate with changing temperature. The accelerated stepwiserelease rate of the sequential type qualifies this device as atime-temperature integrator indicator. As an example, at a temperaturecloser to A_(s) an “x” amount of a substance may be released at a giventime whereas at a temperature closer to A_(f) and for the same time spana “2x” amount of the same substance may be released.

The unfolding shell provides increased design flexibility. In both shelltypes, the shape memory material spring can be located either inside oroutside the shell. In addition, the shape memory material spring can beof configurations other than a coil spring, such as a leaf or torsionspring. Further, only part of the shell wall can be folded, and foldsmay not be symmetrical or of equal length. The concept of creating apath through the shell wall by utilizing the mechanical energy stored inan elastically deformed spring that is restrained by a shape memorymaterial element may also be employed with the unfolding shell.

The coiled shape memory material spring can also be used in compressionand placed either inside or outside the shell. Instead of opening thefolds with increased temperature they are closed. This concept has theadvantage that the substance is released out by pressure as thetemperature changes and a path is created by converting the shell wallsto permeable ones. Alternatively, release can take place throughunidirectional flow valves that allow only outward flow and open up onlywhen the contents of the shell are pressurized by the shape memorymaterial spring. This concept is based on the existence of adifferential pressure between the substance contained in the shell andthe shell's surroundings, and as such it finds applications inenvironments of increased pressures.

FIG. 30. illustrates an alternative embodiment of a shape memorymaterial activated device 200 comprising an accordion type shell 202with a shape memory material spring 204 located outside of the accordionshell 202 and two end reaction members 206. During the shape recoveryprocess, the shape memory material spring 204 contracts, reacts on thetwo end reaction members 206 that in turn squeeze the accordion shell202, pressurize the substance contained inside and forces it out eitherthough preexisting paths on the shell wall or by converting the shellwall into a permeable one. By placing the shape memory material springoutside of the shell, the shell may be divided into several chambers,each having a wall that requires a force of different magnitude for pathcreation. In addition, each chamber may contain a different substance.With a multi-chamber shell, the substance in each chamber may bereleased at a different temperature that lies within the transformationrange of the shape memory material.

Release of a substance from an accordion type shell can take placethough a predetermined path in a weakened area such that the forceexerted by the shape memory material spring creates the path in thisspecific location. The substance may be squeezed out through a clearpath, a valve, a filter or membrane and the like. For viscoussubstances, a clear opening may suffice. In addition, the substance maybe released though several paths in locations away from the shell byconnecting multiple passages such as tubes to the shell to carry thesubstance to different locations. The concept of creating a path bypressurizing or squeezing shell substance is not limited to theaccordion type shell. Any shell formed from a cylinder and a piston,such as a syringe, with the piston activated by a shape memory materialspring is capable of creating similar paths and releasing the substancein an extrusion fashion. In addition, shells may be made of flexible ormalleable material that can change their shapes upon application of aforce by the shape memory material spring, contain the substance andrelease it through a predetermined path. Some of the main advantages ofthis type of shape memory material activated device include the releaseof the substance through multiple paths, control of path size thoughpermeable walls such as filters and membranes, and the release ofsubstance only while the temperature of the shape memory material ischanging. When the temperature stops changing, even though the shapememory material spring has not attained A_(f) yet, pressurization of theshell contents stops and no further substance release takes place.

The shape memory material spring, when trained in a two way shape memoryeffect, can be used to create a path upon cooling to a predeterminedtemperature. Also, the shape memory material spring can be coupled witha bias spring to make the device operational from either the martensiticor austenitic state.

FIG. 31 illustrates a shape memory material activated device 210comprising a shell 212 with a pressurant housing 214 in the form of abellows containing a shape memory material spring 216. With thisconcept, the path is created in an indirect way by utilizing thepressurant housing 214 as an unfolding shell in the form of a bellowsthat is impervious to the surrounding substance contained in the shell212. The shape memory material spring 216 may be placed either inside oroutside of the pressurant housing 214. The pressurant housing 214 andthe shape memory material spring 216 are simultaneously deformed bycompression in the martensitic state. The pressurant housing 214 and thememory material spring 216 are utilized as a pressure generator duringthe shape recovery process and create a path through the wall of theshell 212 to release the substance. The path is created by the forcedvolumetric expansion of the pressurant housing 214 caused by the shapememory material spring 216 undergoing shape recovery. This expansionexerts a pressure on the shell's 212 wall that is transferred though thesubstance contained in the shell. The rate at which the substance isreleased can be instantaneous if the shell walls fracture or separate,or slow if the shell is converted into a permeable one and the substanceis exuded out under pressure. In addition, the substance may be forcedout through preexisting paths on the shell wall, such as interconnectedporosity, by the developing pressure. The type of release rate woulddepend on the design and construction material of the shell. Thisconcept ha multiple advantages. The same pressure generator can be usedwith different types of shells, release or admission of the substancetakes place only during temperature change. In addition, the pressuregenerator can be surrounded entirely by the shell substance or it can bemounted on the shell's inside wall such that the shape memory materialspring can be inserted from outside prior to placing the device inservice. The last attribute allows for shape memory material springs ofdifferent activation temperatures to be inserted in the pressuranthousing prior to placing the device in service. With this process, therelease temperature can be “dialed-in” by the end user and allow for thestorage and transportation of the device at any temperature. Thepressurant housing of this device is not limited to bellows type only;other types of pressurants capable of pressure generation when activatedby a shape memory material and undergo a volume change may be used. Suchpressurant housings comprise any closed volume enclosure impermeable tothe surrounding substance that can undergo a volume change with a shaperecovery force while altering the internal pressure of the shell.

The pressurant concept can be used with a shell to admit a substance byhaving the bellows contract in response to a temperature change, therebycreating a negative pressure inside the shell. The path in this case iscreated by a pressure differential between the outside and the inside ofthe shell such that the shell wall becomes permeable under the existingpressure gradient, drawing the surrounding substance into the shell.Additionally, this device can be activated during the fall oftemperature from M_(s) to M_(f) if the shape memory material spring istrained in a two way shape memory effect or it is coupled with a biasspring. Irrespective of whether the device is activated during thetemperature rise or the fall of the shape memory material, the operatingprinciple remains the same; a change in the temperature of the shapememory material results in a pressure change inside the shell. It isthis change in pressure that creates the path through the shell wall torelease or admit a substance. The amount of substance released oradmitted is controlled by the volume change of the pressurant housingand the minimum pressure differential required to transfer the substanceinto or out of the shell.

Instead of simply releasing or admitting a substance, this device can beused to release a substance when the temperature of the shape memorymaterial activator changes in one direction, and to admit thesurrounding substance when the temperature changes in the oppositedirection. This is a two way substance transport system that isrepeatable with temperature cycling. With multiple cycling, a solid dyecontained inside the shell colors the incoming substance that in turncolors the outside substance when forced out with a reverse temperaturechange. By repeating this operation with temperature cycling, theoutside substance continues to change to a darker color, providing anintegrated indication of the time and temperature for multiple exposuresabove a maximum or below a minimum predetermined temperature.

Additionally, the device may be placed between two adjacent chamberssuch that it admits a substance from one chamber with temperature changeof the shape memory material activator in one direction and releases thesubstance to the second chamber with temperature change of the shapememory material activator in the opposite direction. While the substanceremains inside the shell it can combine with a shell substance to changeits physical and or chemical characteristics. Such combinations canproduce coloring effects, mixing of drug and the like. Alternatively,the device can be used to transport a given quantity of substance fromone chamber to another or to the surrounding environment withtemperature cycling. An application of this concept would be the drugdelivery to a patient from a reservoir. In this application, the firstchamber from which the substance is admitted in the shell constitutesthe reservoir and, the second chamber to which the substance is releasedconstitutes the patient's body. The preferred construction of asubstance transport device, operating by admission and release of asubstance, is to have the part of the shell wall, that is in contactwith the substance to be admitted, capable of becoming permeable in theinward direction only and the part that is in contact with the releasedsubstance capable of becoming permeable in the outward direction.Besides reversing the permeability direction of the two parts of theshell wall, the molecular size of the substance contained inside theshell may change when combined with the admitted substance. In thiscase, depending on the molecular size change, a different degree ofpermeability between the two parts of the shell wall may be sufficientto eliminate the need of reversed permeability. Alternatively, one-wayvalves can be employed at the walls of the shell for the path creationto take place. The valve in contact with the substance to be admittedallows only inward flow, while the one that is in contact with thereleased substance allows only outward flow. If valves are use, apermeable or semi-permeable membrane or filter can be incorporated intheir opening to control type and the rate of the substance that passesthrough them.

FIG. 32 illustrates an alternative embodiment of a shape memory materialactivated device 220. The device comprises a shape memory materialspring 222, a bias spring 224, a support member 225, an abrading element227 and a shell 228 containing a substance. The substance contained inthe shell is a homogeneous or inhomogeneous agglomerated substancecomposed of such forms as grains, particles, powder of uniform ornon-uniform sizes and shapes. The shell 228 may also have a protectivelayer on the outside to prevent any reaction or mixing with itssurroundings. Upon shape recovery, the shape memory material spring 222forces the abrading element 227 to ride along the support member 225 andabrade part of the agglomerated substance away. The abrading element 227may have a sharp edge to force its way into the substance and scrape thesubstance away, or it may be configured with a rough surface to file orgrind the substance away. The abrading process continues as long as thetemperature changes and the shape memory material spring 222 isundergoing shape recovery. When the temperature of the shape memorymaterial spring 222 reverses direction, the bias spring 224 aids thereturn of the abrading element 227 to its original position. During thereturn travel, the abrading element 227 continues to abrade the solidsubstance and release it to the surroundings. In addition to solidparticles, the substance may also be comprised of composite matter suchas gas or liquid globules encapsulated in solid casings.

FIGS. 35 and 36 illustrate embodiments of devices capable of releasingsingle or multiple substances over an extended temperature range. Thistype of release may be continuous or incremental and it is realized bydeforming different parts of the shape memory material by differentamounts. The amount of deformation in the martensitic state influencesthe A_(s) temperature, and for the most part the entire hysteresis curveis shifted upwards to higher temperatures with increased deformation.Generally, if the deformation is excessive, above 8% for the Nitinolmaterial, the hysteresis curve is expanded mostly by extending theA_(s)-A_(f) curve upwards (U.S. Pat. No. 4,631,094). By deformingdifferent segments of a shape memory material such as a wire by variousamounts, each segment will have its own A_(s) temperature. Bysurrounding the shape memory material with a substance and housing it ina shell, release can take place over a large temperature range.

FIGS. 33 and 34 illustrate two types of deformation that can be inducedto shape memory material springs, in wire form, that have straightshapes in the austenitic state. FIG. 32 illustrates a shape memorymaterial spring 232 whose length has been bent to several semicircularsegments. Each semicircular segment, defined as the segment between twosuccessive inflection points, has been deformed uniformly by bending itto a single bend radius with successive segments bent to smaller radii.FIG. 33 illustrates another shape memory material spring 242 whoselength has been bent to several shapes approximating semicircularsegments. However, each segment has been deformed non-uniformly bybending it to a continuously varying radius. The severity ofdeformation, although variable, generally increases progressively withsuccessive segments.

Shape memory material springs can also be deformed from a bent shape toa straight shape in the martensitic state. In other words, the shapesshown in FIGS. 32 and 33 could be the austenitic state shapes with themartensitic shapes being straight. This may be desirable for specificapplications such as ease of assembly or incorporation into anotherdevice. One such application would be the assembly of different shells,each having an essentially hollow cylindrical configuration, into astraight shape memory material spring in a similar fashion as thestringing of beads. It should be understood that shape memory materialsare not limited to these two modes of variable deformation illustratedin FIGS. 33 and 34.

When the temperature of the shape memory material springs 232 and 242 israised, the segments subjected to the least amount of deformation willbegin the shape recovery process first. Each semicircular segment of theshape memory material spring 232 will begin the shape recovery at adifferent temperature. In this manner, shape recovery will progresssequentially from segment to segment as the temperature continues torise. On the other hand, shape recovery in the shape memory materialspring 242 will begin simultaneously in several locations of thedifferent segments that have been subjected to the same amount ofdeformation. While the temperature is raised, varying lengths of eachsegment will be undergoing shape recovery simultaneously. In the firstshape memory material spring 232, the beginning of the shape recoveryprocess would appear to be orderly while in the second one 242 it wouldappear to be random. However, in both cases the beginning of thisprocess is predetermined by the localized degree of deformation. In thefirst case, the beginning of shape recovery is sequential and segmented,while in the second one, it is simultaneous and continuous.

FIGS. 35 and 36 illustrate the variable deformation concept that canlead to applications requiring extended release. FIG. 35 illustrates ashape memory material activated device 250 comprising a plurality ofshells 252 adjacent to each other and a shape memory material spring254. FIG. 36 illustrates a shape memory material activated device 260,similar to 250, comprising a plurality of shells 262 adjacent to eachother and a shape memory material spring 264. The shape memory materialsprings 254 and 264 of the two devices have been deformed, from thestraight austenitic state, to different configurations in themartensitic state. The two shape memory material springs 254 and 264have been deformed similarly to 232 and 242, respectively. Initiation ofpath creation in the first device 250 takes place sequentially betweenthe successive shells as the temperature of the shape memory materialspring is raised. Initiation of path creation in the second device 260takes place simultaneously in different locations of all the shells andcontinues to move to other locations as the temperature of the shapememory material spring is raised. The determining factor for pathinitiation in both cases is the amount of localized deformation inducedin the martensitic state. As the amount of deformation increases, sodoes the A_(s) temperature along with the path initiation. Each shell,of either device, may contain a different substance such that device 250begins the release of the different substances sequentially as thetemperature increases while device 260 begins the release of apredetermined group of different substances simultaneously. The releasefrom each shell may be instantaneous such as in the case of gases andliquids where a single path may be sufficient to release the totalsubstance, or continuous, as in the cases of solids where multiple pathsare needed to release the total substance. In the latter case, a singleshell of device 260, having its shape memory material spring 264deformed to variable amounts, will release the substance over a widertemperature range as compared to device 250. For devices comprising aplurality of shells, with the paths in each shell initiated at a singleor multiple temperatures, a predetermined release profile over a widetemperature range can be produced.

In fabricating the extended release devices, the substance can beadhered to the shape memory material and the shell can be built aroundthe substance. Some of the methods used to apply the substance are; apowder slurry that is subsequently dried, a gas that is condensed andfrozen or a liquid that is frozen. Once the substance is applied, theshell can be build around the substance by methods such as spraying ordipping and drying or curing. It is obvious that no heat should be usedthat would result in either partial or full shape recovery of the shapememory material activator. Path creation can take place by any of themethods described herein that result in microscopic or macroscopic sizeopenings in the shell wall through which the substance is released.

Instead of a having a single shell with a multi-deformed shape memorymaterial, several shells each containing a different substance can bebuild around a single multi-deformed shape memory material. With thisconcept, the path in each shell will be created at a differenttemperature with the net effect of producing different colors atdifferent temperatures or releasing different types of drugs andquantities. The individual shells may or may not share a common wall.The use of a single multi-deformed shape memory material to produceextended release can replace several individual shells each having theirshape memory material deformed by different degrees or each containing adifferent substance. In addition, a gradually deformed shape memorymaterial with several shells will guarantee continuous release over alarge temperature range.

This same concept can be used with a shape memory material trained intwo way shape memory effect to create the path upon cooling to belowM_(s). In this case, assembly of the device must take place in theaustenitic state after completion of the shape recovery in order toavoid release during heating from A_(s) to A_(f). Typically, reverserecovery is limited to nominal shape recovery strains and is notapplicable to extended release beyond these limits. The same concept ofreleasing the substance during cooling can also be used with a biasspring coupled to the shape memory material spring.

Extended release is not limited to a single straight wire deformed bybending, other product forms such as sheet, strip, rod, bar or tube,deformed by other methods such as stretching, compressing, twisting canbe used. In addition, the shape memory material may surround thesubstance to be released, as may be the case of a perforated tube. Inthis case, as an example, the shape memory material tube is deformed inthe martensitic state, diametrically to various degrees of severityalong its length, is filled with a substance, and has its perforationsand its two ends sealed. Different length segments can be filled withdifferent substances and be separated with dividing materials to formindividual shells and to isolate one substance from the next. Duringheating, the localized strains developed in the shape memory materialcreate paths through the sealed perforations to release the substance.The path initiation process progresses until the most deformed regionsundergo shape recovery.

In a second example, a wire that is stretched to various degrees,incrementally or continuously to produce increased amounts ofdeformation along its length, can be used as a single shape memorymaterial activator to peel the wall and create a path in several shellssequentially with rising temperature. In utilizing the extended releaseconcept, it should be understood that transformation temperatures areaffected by the stress applied to the shape memory material whileundergoing shape recovery. For example, in the case of the peelableshells, once the part of the shape memory material wire with the lowestA_(s) temperature begins to undergo shape recovery, a constrained forceis developed during the process of peeling and the whole wire is put intension. As different parts of the wire undergo shape recovery withincreasing temperature, the magnitude of the tension varies andinfluences the transformation temperatures of the balance of the wire.In addition, depending on its magnitude, it may further deform theportions of the wire that have not yet recovered their shapes. Besidesstretching a shape memory material wire or rod by varying amounts,different length segments may be stretched by varying amounts whileothers may be shrunk by varying amounts such that during shape recoverythe overall length undergoes multiple expansions and contractions in apredetermined manner. Different modes of deformation can be used toproduce shape recoveries to meet specific application requirements.

FIG. 37 illustrates a third example of a shape memory material activateddevice 270 that releases a substance over a wide temperature range,comprising a shell 272 and a shape memory material spring 274. The shapememory material spring 274 is integrated into the wall of the shell 272that has a tubular form. The shape memory material spring 274 has beendeformed in the martensitic state by varying amounts along its length toenable it to create multiple paths over a wide temperature range. Theshape memory material spring 274 is embedded along the length of asealed axial seam in the shell 272 and it is through this seam that thepath is created to release the substance. The view shown in FIG. 37 is across sectional view perpendicular to the longitudinal axis of theshell. The shell can be compartmentalized, similarly to devices 250 and260, to create multiple shells such that the path creation for differentcompartments takes place at different temperatures. The advantage ofthis concept is that the length of shape memory material is independentof the shell's diameter and is effectively independent of the quantityof the substance contained in the shell. In devices where the shapememory material is embedded in the shell wall, any possible slippagethat may compromise its ability to create a path may be avoided by theintroduction of geometric features on the surface of the shape memorymaterial such as projections, indentations or twists that will aid itsanchoring.

Extended release offers the advantage of providing an analog type pathcreation and release with increasing temperature. Assuming “other thingsbeing equal”, the path creation rate and substance release would dependon the heating rate of the shape memory material as well as thedeformation rate change along the length of the shape memory material.Useful applications of this concept include, but are not limited to,dyes and drugs. A dye released can be of a continuously changing colorsuch that the color at any given time is indicative of the temperatureof the shape memory material. This type of device offers the advantageof continuous temperature indication with increasing temperature for anextended temperature range, while as a drug release device it offers acontrolled release of different drugs, group of drugs or the same drugwith varying concentration for an extended temperature range. Further,another advantage that this type of device offers is that release can becontrolled in an on-off fashion by the application and removal of heatwithout the incorporation of switches or valves. Path creation ceasesonce the temperature of the shape memory material is longer increasingand resumes again with further increase in temperature. This procedurecan be repeated several times each time increasing the temperature to ahigher level. Extended release of drugs can be used in many applicationssuch as implants and transdermal delivery systems.

The shape memory material used as an activator in these devices can beheated by various methods such as ambient heat, directly or indirectlyapplied heat and resistive heat. The input of electric energy in theform of resistive heat used to heat these devices can be controlled toallow specific segments of the multi-deformed shape memory materialactivator to undergo shape recovery and create paths. By resuming theheating to increasingly higher temperatures, more segments undergo shaperecovery that results in more path creations and release of moresubstances.

Variable Volume Shell

FIGS. 38 to 43 illustrate two shape memory material activated devices,280 and 300 respectively, whose shells change volume with each releasecycle. This variable volume shell concept utilizes two variable volumecontainers such as bellows, one housed inside the other. The innerbellows forms the pressurant housing while the outside one forms theshell. The pressurant housing contains a shape memory material springcoupled with a bias spring, all together comprising a pressuregenerator, while the shell contains the substance to be released. As thetemperature of the shape memory material spring rises and undergoes ashape recovery, it overcomes the resistance offered by the bias springand in the process applies a pressure to the surrounding substance. Theapplied pressure is considered positive when the shape memory materialspring increases the volume of the pressurant housing, that in turnincreases the substance's pressure. It is considered negative when asuction is created by a shrinking pressurant housing when the shapememory material is contracting. The pressure transmitted to the shellwalls through the substance contained in the shell creates single ormultiple paths through these walls to release or admit the substance. Inessence, the shape memory material creates these paths indirectly. Thepath creation can be permanent or temporary. Permanent paths areintended for a one-time release and are irreversible. Temporary pathsare intended for multiple releases and are reversible. Temporary pathsinclude the conversion of the shell wall to a permeable orsemi-permeable wall, and the opening of a one way valves. For thesubstance to be released the valves open outward, while for thesubstance to be admitted they open inward. Pre-existing paths includepermanently permeable or porous walls through which the substance canonly flow through under pressure such as is the case during theexpansion of the bellows. The direction of substance flow determines thetype of variable volume shell. The shell is considered a shrinking shellwhen the substance flows outward and a growing shell when it flowsinward.

The shrinking shell concept is demonstrated in FIG. 38, whichillustrates a variable volume shell shape memory material activateddevice 280 comprising a shape memory material spring 282, a bias spring284, a pressurant housing 286, a shell 288 with a plurality of fins 292,a valve 294, and a plurality of guide rods 296, each configured with aplurality of teeth 298. The fins 292 are configured with holes to allowthem to ride on the guide rods 296, in a curtain fashion, as the shell288 changes volume. The teeth 298 of the guide rods 296 are configuredsuch as to allow the fins 292 to travel in one direction and to precludereverse travel. The shape memory material spring 282 and the bias spring284 are housed inside the pressurant housing 286, which in turn ishoused inside the shell 288. As the temperature of the shape memorymaterial spring 282 rises and it undergoes shape recovery, it overcomesthe resistance offered by the bias spring 284 and in the process ofexpanding, forces the pressurant housing 286 to expand also and createsthe path to release the substance.

FIG. 39 illustrates the variable volume shell shape memory materialactivated device 280 while the shape memory material spring 282 isundergoing shape recovery. The pressure exerted on the substancecontained in the shell forces the creation of a path to release thesubstance. In this case, the path is created through the valve 294 thatis a one-way valve and allows outward flow only.

FIG. 40 illustrates the variable volume shell shape memory materialactivated device 280 while the shape memory material spring 282 iscooling down to the martensitic state and is undergoing reverse shaperecovery. During cooling from austenite to martensite, the shape memorymaterial spring 282 is forced to contract by the bias spring 284, and inthe process, the pressurant housing 286 is forced to shrink. Thisreduces the pressure inside the shell 288 relative to the surroundingsand in turn it is forced to shrink. Shrinkage is allowed only in theaxial direction by the guide rods 296 that function as guides as well asrestraints to prevent reverse movement. Each time the heating-coolingcycle is repeated, the shell shrinks by a volume equal to the volume ofthe released substance. This process continues until the bellowsencounters the end and the pressurant housing 286 can no longer expandand contract.

The growing shell concept is shown in FIG. 41, which illustrates avariable volume shell shape memory material activated device 300comprising a shape memory material spring 302, a bias spring 304, apressurant housing 306, a shell 308 with a plurality of fins 312, avalve 314 and a plurality of guide rods 316, each configured with aplurality of teeth 318. This device 300 is similar to device 280 withthe exception that the shell grows with temperature cycling as it admitsa surrounding substance. The shape memory material spring 302 contractsinstead of expanding during shape recovery, shrinks the pressuranthousing 306, and creates a path to admit the substance while the shell308 is restricted from shrinking by the guide rods 316. The teeth 318 ofthe guide rods 316 are oriented in the opposite direction of the teeth298 in device 280.

FIG. 42 illustrates the shape memory material activated device 300 whilethe shape memory material spring 302 is undergoing shape recovery. Thesuction created by the volume reduction of the pressurant housing 306forces the creation of a path to admit the surrounding substance. Inthis case, the path is created through the valve 294, that is a one-wayvalve and allows inward flow only.

FIG. 43 illustrates the shape memory material activated device 300 whilethe shape memory material spring 302 is cooling down to the martensiticstate, undergoing reverse shape recovery. During cooling from austeniteto martensite, the shape memory material spring 302 is forced to expandby the bias spring 304 and in the process, the pressurant housing 306 isforced to expand. This increases the pressure inside the shell 308relative to the surroundings and in turn it is forced to expand and toclose the valve 314. Expansion is allowed only in the axial direction bythe guide rods 316 that function as guides as well as restraints toprevent reverse movement. The process of alternate substance admissionand shell expansion continues with temperature cycling until the bellowsencounters a stop or until the shell is full and it is not capable offurther expansion.

The concept of the shrinking and growing shell can be used to release oradmit a substance during cooling from the M_(s) temperature instead ofheating from the A_(s) temperature. This is accomplished simply byreversing the direction of shape recovery in each case. The guide rods,inserted in the holes of the fins, allow the shell to travel axially inone direction and restrict it from traveling in the reverse direction.The conical shape of the teeth allow the fins to slide easily through,from apex to the base, but prevent them from sliding backward. Slidingmay entail enlargement of fin holes by stretching while going throughthe teeth. Instead of using guide rods placed on the outside, a hollowshell with a hollow pressurant housing can be used along with theincorporation of a single center guide rod configured with a pluralityof teeth.

In all cases, the bias spring may be eliminated as a separate part ifthe pressurant housing also serves as the bias spring. This isespecially true when the pressurant housing is formed as a bellows thatcan expand and contract elastically, and in the process, store andrelease mechanical energy. The mechanical energy is stored during theshape recovery process when the shape memory material spring deforms thepressurant housing elastically, and it is released during cooling whenit is utilized to deform the shape memory material spring back to themartensitic shape. Alternatively, in cases where it is not desirable tohave the pressurant housing perform as a bias spring, it may be filledwith a compressible fluid that would act as a bias spring. Further, thepressurant housing and the bias spring may be combined into one part,made of material such as an elastomer, capable of undergoing volumechanges with the application and removal of the shape recovery force.The elastomer may have any shape that will accommodate the shape of theshape memory material spring. For example, a shape memory material tubemay be filled with an elastomeric material to act as a couple. The tubemay be deformed in the martensitic state, axially or radially, andfilled with the elastomeric material. During shape recovery, the shapememory material tube forces the elastomer to change shape, changes thepressure in the shell, creates a path to release or admit the substance.During cooling, along the M_(s)-M_(f) path, the elastomer acts as a biasspring and deforms the shape memory material back to its starting shape.The term “pressurant” as used herein implies a part or assembly capableof changing its volume with the application of a force such as the onegenerated by a shape memory material element and in the process changethe pressure of its surroundings when placed in a closed volumecontainer such as inside a shell.

The variable volume shell concept can be accomplished by alternativemeans besides the ones described herein. FIG. 44 illustrates an exampleof an alternative variable volume shell shape memory material activateddevice 320 that utilizes restraining means other than the toothed guiderods. This device 320 is similar to devices 280 and 300, with theexception that the guide rods along with the teeth have been replacedwith a ratchet 324 and a detent 322 restraining system. The detent 322is fixed while the ratchet 324 moves along with the shell in onedirection only. Alternative guides and restraining concepts includetracks with fins and frictional effects, similar to ones describedelsewhere in this specification. Further, a cylinder, having an internalsurface configured to allow the shell to travel in one direction only,may be used to house the device and replace the function of the guiderods. In this case, the fins of the shell ride along the inside surfaceof the cylinder. The morphology of the inside surface of the cylindermay contain features such as knurled marks, gear teeth orcircumferential fins, preferentially oriented to allow the shell totravel in one direction with minimal resistance and to prevent itstravel in the reverse direction.

The variable volume concept is not restricted to bellows. Any type ofcontainer made of a single or multiple parts, whose volume can vary,preferably in one direction, can be utilized as a shell or a pressuranthousing. FIG. 45 illustrates another alternative variable volume shellshape memory material activated device 330 whose shell comprises twoconcentrically located, axially sliding, half shells: an inner halfshell 332 and an outer half shell 334 sealed with a plurality of O-rings336. Only the outer half shell 334 travels, in a telescoping fashion,with temperature cycling. The other shell, the inner half shell, 332remains stationary at all times.

The pressure generator, comprised of the pressurant housing with theshape memory material and the bias spring, can be placed either insideor outside of the shell. FIG. 46 illustrates device 340, whose pressuregenerator comprises a shape memory material 342, a bias spring 344 and apressurant housing 346 all placed outside of the shell. Here thepressurant housing 346 pressurizes the shell 348 from the outsidewithout being in contact with substance. This concept assures release ofall the shell contents. One end of the pressurant housing, whetherplaced inside or outside of the shell, may be open to the outsidethereby eliminating any biasing force due to internal pressure. Devicesutilizing the open ended pressurant housings make the shape memorymaterial spring and the bias spring accessible from the outside. Thisallows installation of the springs prior to placing them in service.This is beneficial as the devices may be maintained at any temperatureprior to placing them it in service and allows for the selection ofshape memory material and bias springs to match the release temperaturerequirements for a specific application.

Alternatively, the whole device maybe be enclosed in a pressurized andhermetically sealed enclosure with only the area encompassing the pathcreation exposed to the outside. Here the enclosure's pressuredetermines the amount of substance to be released. The enclosurepressure decreases as more substance is being released and in turn,release per cycle is decreasing. In essence, a variable (decreasing)release is produced with cycling.

The shape memory material spring does not have to be a coil spring. Itmay be any shape including a simple straight element that is capable ofperforming repeated work with temperature cycling either by itself or inconjunction with a bias spring. In addition, the shape memory materialmay comprise part of the whole pressurant housing or be the pressuranthousing. Typically, Nitinol alloys recover up to 8% of their strainduring the transformation process from martensite to austenite. Theamount of substance released with each cycle depends on the volumetricexpansion of the pressurant housing. With a linear expansion of a fewpercent of the total length of the pressurant housing, the contributingvolume change factor becomes its diameter. The amount of substancerelease with each temperature cycle can be optimized through theselection of the shape memory material spring's geometry and size alongwith the pressurant housing's diameter.

Alternatively, restraining the pressurant housing by a predeterminedamount as it expands and contracts controls the amount of substancereleased or admitted. FIG. 47 illustrates the concept of the restrainedpressurant housing. In addition to the shape memory material spring andthe bias spring, the pressurant housing 350 houses two interlockingstops, a male stop 352 and a female stop 354. The two stops moverelative to each other in opposite directions with the expansion andcontraction of the pressurant housing. However, their movement islimited to a maximum distance “d” that determines the amount ofsubstance to be released. Alternatively, other restraining methods maybe use and the distance “d” may be fixed or adjusted by the user priorto placing the device in service.

As with other devices presented herein, the substance can be released tothe surroundings or to an enclosure for further enhancements of thedevice. Such enhancements include mixing with the substance of theenclosure to produce effects such as color changes that are indicativeof the temperature exposure history. Color changes can be detectedthrough a transparent window in the enclosure. Besides color change,temperature exposure history may be indicated with a pointer showing theshell's length change. FIG. 48 illustrates the temperature historyindicating elements on a device similar to 280. The indicating elementsof device 360 comprise an enclosure 362, a graduated scale 364 and apointer 366. The enclosure 362 changes color with increasing release ofthe substance. The color change may be visible though a transparentwindow of the enclosure. The pointer 366 is mounted on the end fin ofthe shell and travels along with the shell. As it travels, it indicatesthe length change of the shell on the graduating scale 364. The lengthchange of the shell indicates the total substance that has been releasedwhich, in turn, is indicative of the temperature exposure history of theshape memory material.

One of the main advantages of the volume changing shell concept is thefact that the substance is being released or admitted only while theshape memory material is subjected to a temperature change within apredefined temperature range. During this temperature change, it forcesthe pressurant housing to change volume resulting in the path creationthrough the shell's wall. In the case where the path is created duringshape recovery, once the A_(f) temperature is reached the pressuranthousing stops changing volume and path creation ceases. The same applieswhen the path is created during the cooling part of the temperaturecycle. Once the M_(f) temperature is reached, the pressurant housingstops changing volume and path creation ceases. Flow of the substance inor out of the shell is not restricted to valve paths. The substance mayflow through paths created by conversion of shell's wall or sections ofthe wall to permeable or semi-permeable paths. These wall parts may berendered permeable only during the path creation process when a pressuredifferential exists between the contents of the shell and itssurroundings. Any substance that is detectable by the senses or not canbe released though any path created through the shell's wall by a shapememory material activator. Further, a permeable or semi-permeablebarrier, such as a filter or membrane, may be incorporated in theopening of the valves. Opening of the valves makes the substanceaccessible but the accessibility rate is controlled by the barrier.

Medical applications include drug delivery devices such as transdermalsand implants. In all cases, the substance is released only while theshape memory material is undergoing shape recovery or reverse shaperecovery. This is advantageous as the amount of substance release isindependent of the width of the hysteresis. In the case of bodytemperature activated release, i.e. fever, the amount of releaseincreases as the fever increases, thereby providing the body with moreantipyretic drug. In the case of implanted drug delivery systems, theA_(f) temperature is the limiting release temperature. Release stops atthis temperature, irrespective of the heating energy provided to theshape memory material either externally or internally. The width ofhysteresis has no influence on the amount released, as no furtherrelease takes place once the A_(f) temperature is reached. For implantdevices, this concept offers the advantage that with each temperaturecycle, there is a predefined amount of substance released. This amountis independent of energy input, above a minimum level, and independentof the time the shape memory material stays at a given temperature.Also, because the shell contains a finite amount of substance, the drugcan not be abused. Once depleted, the shell can not be refilled as theshell guide rods prevent its reverse movement.

Variable shell type temperature indicators provide a cumulativetemperature record of exposure of the shape memory material to apredefined temperature range. Exposure may be through the wholetemperature range or part of it. The exposure record is indicated by acolor change of a substance viewed through the transparent window. Theintensity of color changes with increased temperature exposures. Thetotal amount released provides an integrated record of the shape memorymaterial temperature exposure. This device integrates the release withrespect to temperature over a predefined range. Besides the change incolor intensity with temperature cycling, a new color can also beproduced. The new color is produced by utilizing a viscous substance inthe shell that is structured in layers of different colors. Once thefirst layer has been released with temperature cycling, the next layerbegins to be released with repeated temperature cycling therebyproducing a new color. This process continues to produce a new coloreach time a complete layers of a specific color has been released. Theutilization of multiple colors extends the life of the device byallowing interpretation of temperature exposure by color differentiationin addition to color intensity. In addition to filling the shell with amulti-color substance in layers, the substance may have a colorgradient. In all devices, drug delivery, indicators and others, thesubstance quantity released is independent of the heating or coolingrates of the shape memory material.

Renewable Shell

FIG. 49 illustrates a shape memory material activated device 370comprising a shape memory material spring 372 and a bias spring 374housed in a pressurant housing 376 that is housed in a shell 378equipped with an outflow valve 382, an inflow valve 386, and a supplyreservoir 384. The device 370 is similar in operation to device 280illustrated in FIG. 38, with the exception that the shell is of fixedvolume. This device is capable of refilling the substance contained inthe shell 378 after each release and as such, its service life is notlimited to a given amount of substance contained in the shell.

FIG. 50 illustrates the shape memory material activated device 370 whilethe shape memory material spring 372 is undergoing shape recovery. Thepressure exerted on the substance contained in the shell forces thecreation of a path to release the substance. In this case, the path iscreated through the outflow valve 382 that allows one-way flow only.

FIG. 51 illustrates the shape memory material activated device 370 whilethe shape memory material spring 372 is cooling down to the martensiticstate and is undergoing reverse shape recovery. During cooling fromaustenite to martensite, the shape memory material spring 372 is forcedto contract by the bias spring 374 and in the process, the pressuranthousing 376 is forced to shrink. This reduces the pressure inside theshell 378 relative to the pressure of the supply reservoir 384 andcreates a path to admit the substance from the reservoir. The path iscreated through the inflow valve 386 that allows one-way flow only.

This shell is capable of continuously renewing its substance. With eachtemperature cycle, it releases the substance to its surroundings or toan enclosure during the first half of the cycle and admits the same or adifferent substance from the reservoir during the second half of thecycle. To assure continuation of the process of releasing and admittingthe substance the supply reservoir, depending on the application, may berefilled by means such as a supply tube, a syringe or a pump.

FIG. 52 illustrates a shape memory material activated device 390comprising a shape memory material spring 392, a bias spring 394, apressurant housing 396 equipped with an outflow valve 402 and an inflowvalve 404, all housed in a shell 398 that is connected to a supply line406. In this case, the pressurant 396 functions mostly as a means forsubstance transfer and a pressure generator. The outflow valve 402 andthe inflow valve 404 attached to opposite ends of the pressurant housing396 open and close out of phase with the heating and cooling cycle ofthe shape memory material spring 392, while the shell is being suppliedcontinuously with the same or a different substance by the supply line406.

FIG. 53 illustrates the shape memory material activated device 390 whilethe shape memory material spring 392 is undergoing shape recovery.Initially, the pressurant housing 396 is filled with the shell'ssubstance, during shape recovery its internal pressure increases as thepressurant housing 396 is shrinking and creates a path through theoutflow valve 402 to release the substance while its volume isdecreasing. The path may also be created by other means such aspermeable or semi-permeable shell walls or one-way flow membranes.Release may also take place through pre-existing paths through which thesubstance flows only when there is a minimum pressure differentialbetween the shell's surroundings and the inside of the pressuranthousing. Once the pressure differential drops below the minimum value,or the two pressures equalize, the flow stops.

FIG. 54 illustrates the shape memory material activated device 390 whilethe shape memory material spring 392 is cooling down to the martensiticstate and is undergoing reverse shape recovery. During cooling fromaustenite to martensite, the shape memory material spring 392 is forcedto contract by the bias spring 394 and in the process, the pressuranthousing 396 is forced to expand. This reduces the pressure inside thepressurant housing 396 relative to the pressure of the shell 398 andcreates a path through the inflow valve 404 to admit the substance whileits volume is increasing.

In both devices 370 and 390, by reversing the direction of the one-wayvalves the substance can be admitted into the shell and released into asupply reservoir, thereby reversing the direction of the mass transfer.In addition, the release or admission of the substance can take placeduring either the heating or the cooling part of the temperature cycle.Simply, in one case the shape memory material expands during heatingwhile in the other it contracts.

Similarly to the variable volume concept, the renewable shell conceptpresents the advantage of path creation and substance release only whenthe shape memory material undergoes shape change, either by a shaperecovery force or by a biased force. The amount of released substance iscontrolled by the volume change of the pressurant housing. In addition,the refill substance admitted in the shell may be of changing physicalor chemical characteristics, that, when combined with the shell'ssubstance, produces a new color, a modified drug or higher strength drugor some other new feature with each release.

Both concepts of variable volume and renewable shell may be used forsimilar applications. In addition to releasing a substance, eitherdevice may be utilized to change the volume and or the pressure ofanother reservoir. This is a desired benefit in cases where there is aneed to change the volume of a reservoir of a given geometry in apredetermined direction or orientation. FIG. 55 illustrates a device 410where the release of the substance expands a hollow tube with axialfolds 418 radially. A renewable shell device similar to 370 coupled witha tube 414 that contains a unidirectional flow valve 416 are utilizedfor this purpose. As the substance is released into the reservoir, bothits outside and inside diameters increase. The radial expansion may beutilized to relieve the pressure around an object or to increase it ifthe substance's flow is reversed and the reservoir begins to shrinkradially. Further, the reservoir may release the substance to itssurroundings through permeable walls and the like, enabling the deviceto act as both a substance release and a mass distribution device.

Time Dependent Temperature Activated Systems

FIGS. 56-68 relate to time dependent temperature warning systems as willbe described below. The time dependent temperature warning systems canbe used as an indicator of the time that the device has been exposedabove or below a predetermined temperature. The time dependent systemsmay also be used as a drug delivery system, in which case the system isconsidered as a time compensating drug delivery system.

FIGS. 56-59 illustrate one embodiment of a time dependent device 500having a shell 502 that consists of two members capable of creating apath upon separation. The first member is a closing part 506 in the formof a conical plug and is in contact with a second part 505, the sealer.A shape memory material activator 508 applies pressure and keeps the twomembers 505 and 506 in contact along a surface 504. Contact between thetwo members is maintained until a predetermined temperature is achieved.The device 500 also preferably includes a seal 510 bonded to the sealer505, made of a material such as an elastomer capable of swelling throughabsorption of liquid. The device 500 utilizes the same concept as the“shell” described above, i.e. release and/or mixing two substances.However, in the present case, a shape memory material spring 508 is usedthat is trained in two way shape memory effect. The substance to bereleased from the shell 502 may be provided within the sealer 505 and/orwithin the closing member 506. However, for purposes of simplicity inthe following discussion, the substance to be released, called thesource, will be considered to be contained within the closing member506.

In the embodiment of FIGS. 56-59, the path created through the shellwall, to release the substance contained within the closing member 506and/or the sealer 505 at the predetermined temperature, is notpermanent. The path is created by the controlled separation of the shellinto two parts, the sealer 505 and the closing member 506. The shellopens every time the predetermined temperature is reached, remains openas long as the temperature does not drop below this level, and closesonce the temperature drops. While the shell 502 remains open, thesubstance is released continuously but the release stops when the shellcloses. With each opening the drug or other substance may be released toa surrounding reservoir (not shown) in a continuous manner.

FIG. 56 illustrates the sealer 505, the closing member 506, and theshape memory material activator 508 in a closed position before aninitial opening. FIG. 57 illustrates an initial opening of the shell 502and the creation of a path along the contact surface 504 by the movementof the closing member 506 in response to achieving a predeterminedtemperature. After opening, the seal 510 provided in the opening 504comes into contact with the fluid of the enclosure and begins to swellas shown in FIG. 58. When the predetermined temperature for opening isno longer achieved, the closing member 506 moves back and comes intocontact with the seal 510 and closes the path, thereby preventingpassage of fluid through the opening 504.

According to the embodiment of FIGS. 56-59, if the substance containedin the shell 502 is in the solid state, the surrounding reservoir (notshown) should contain a fluid to dissolve it. On the other hand, if thesubstance contained in the shell 502 is in liquid state it can bereleased to either an empty reservoir to be delivered to the patientwithout further mixing, or to a fluid filled reservoir to be mixed withfluid prior to delivery. Control of the mixing rate in the solid/liquidcase is by direct contact whereas in the liquid/liquid case control ofthe mixing rate is done through a membrane or filter which is part ofthe sealer's and/or closing member's wall. Because of the continuousrelease, irrespective of its solid or liquid phase and irrespective ofwhether it is a dye or a drug, the substance within the shell will beconsidered as the “source” herein. The shell's liquid source should beunder positive pressure relative to its surroundings, with no gasentrapment, to assure wetting of all membrane walls and a constantinterface between the two fluids irrespective of orientation.Additionally, pressurization prevents the reverse flow of the substanceoutside of the shell in the enclosure into the source's housing. Reverseflow can also be prevented with the use of a one way membrane. Theprinciple of osmosis can be utilized to transport the source through themembrane wall provided that the membrane material and liquids of bothshell and enclosure are selected such as to satisfy the requirements forosmosis to take place. Pressurization can be accomplished by severalmeans such as the use of a spring as a piston, a gas bladder, acompressed elastomer or a compressed superelastic spring pressuring thedye enclosure. The shape of the shell's solid state source or its liquidstate container can be conical (as shown), spherical, or any shape thatcan be sealed when pressed against an organic material such as anelastomer having springback properties with minimum compression set orcreep. Basically, the source forms the male part and the sealer thefemale part of the device. When in contact with each other there is noopen path and no release of the substance from the shell.

If the seal 510 is made of material that swells with exposure to fluids,the swelling (increase in volume and thereby linear dimensionalincrease, distance d in FIG. 59) will account for any loss of shapememory with cycling of the shape memory material activator 508.

If the source is in the solid state and in the form of a cone, sphere,or other shape, it must be dissolved uniformly such that it can besealed at the end of each cycle. In the case of a time compensating drugdelivery system, the solid state drug source can contain a gradient ofthe active ingredient such that the released drug increases in potencywith increased exposure time. In the case of a time integrator indicatorthe dye can consist of several layers of different colors (with onecolor being exposed at any given time) so that different colors areproduced with increased exposure time. Color change will be indicativeof the time exposure above or below the predetermined temperature. FIG.60 illustrates a device similar to device 500, illustrated in FIG. 56,containing a variable composition source 509. The variation incomposition is depicted with the density of the dots in FIG. 60. Forbetter accuracy, the surface of the seal 510 in contact with the source506 must be sealed so that any absorbed liquid will not continue todissolve the source. Also, the shape of the drug source must be designedsuch that the liquid at the interface is displaced during the completionof the cycle, i.e. upon return to the martensitic state. One way this isachieved is to allow for more cushion at the first contact point, i.e.peak of cone or sphere, and decrease the amount of cushioning as thecontact continues. An example of this configuration is shown in FIGS. 63and 64 of which FIG. 63 illustrates a partially recovered position andFIG. 64 illustrates an open position. In other words, it may bepreferred to prevent either instantaneous contact or reverse (base topeak) contact.

Instead of using a shape memory material trained in two way shape memoryeffect, the cycling can also be accomplished with the incorporation of abias spring 520 along with the shape memory material spring 508, asshown in the embodiment of FIG. 61. The system of FIG. 61 will assurethat there is sufficient pressure to keep the source sealed during theshell's closing period by the use of the bias spring 520.

The time integrator indicator devices of FIGS. 56-68 are capable ofintegrating exposure to a single temperature or temperature range withrespect to time. Additionally, they are capable of giving more weight tohigher (or lower) temperatures. In other words they are capable ofnon-linear integration of temperature with time. The time-temperaturehistory can be presented through a color change of the indicator.

The same concept can be used without the swelling effect. In this casethe seal must provide the cushioning and sealing, and must exhibitminimal creep in the expected operational temperature range. Again, abias spring can be used to minimize the amnesia of the shape memorymaterial activator and assure sufficient contact pressure to displacethe fluid from the sealer/drug source interface.

In both cases, swell and no swell of the seal 510, the source 506 can bemade the stationary member and the sealer 505 the moving one. Inaddition, as shown in FIG. 62, one or more holes 530 can be incorporatedin both the sealer 505 and the source or closing member 506 to eliminatethe possibility of vacuum locking.

The concept used for the time dependent shell described above withrespect to FIGS. 56-62 can be extended to become a time and temperaturecompensating drug delivery system and a time and temperature integratorindicator. This requires one of the two following design changes.

The first change requires selection of the source material, membrane (ifone is used) and, enclosure fluid such as to control the release ormixing rates with respect to temperature. In other words, release isboth material and temperature dependent. With this system, at a constanttemperature above A_(s) and with increasing time the drug release rateremains constant as time goes by. However, the release rate increases asthe temperature increases. If a solid state drug source is used which isbuilt of different strength layers, the release rate will be increasingincrementally, as each layer is dissolved, with either time itself atconstant temperature or time and temperature. The strength levels andthe rate of change must be calibrated for specific applications, as eachapplication requires different temperatures and times. This concept hasonly a lower temperature limit. The temperature application range isbounded only at the low end which is the A_(s) temperature. Above thistemperature the path through the shell wall remains open and release ordissolution of the source is continuous. Upper bound is only limited bymaterial capabilities.

The second change requires modification of the geometry of the sourcesuch that there is a progressively larger gap, tip to base, between thesealer and the source, as shown in FIGS. 63 and 64. As the temperatureincreases above A_(s), the shape recovery progresses and the source orclosing member 506 is withdrawn away from the seal 510, the interfacearea between the source and the fluid of the enclosure increases. Thisincrease results in an increased release (or mixing) rate that isproportional to the increase in the interface area. By varying thegeometry of the source (conical, spherical, etc.) the rate of theinterface area change is controlled with respect to the withdrawing rateof the source. In return, the degree of linearity and the slope of theA_(s) to A_(f) and M_(s) to M_(f) segments of the hysteresis curve, asinfluenced by the bias spring, determine the withdrawal rate of thesource. With this concept, at constant temperature above A_(s) therelease rate stays constant (assuming linearity with respect to mixingratio) but it increases with increasing temperature. Applicability ofthis concept is limited to the temperature range of the hysteresis curveof the shape memory material as there is no further displacementproduced by the shape memory material above A_(f) and therefore nofurther temperature compensation takes place. During cooling, theprocess is reversed except that the M_(s) to M_(f) temperature segmentof the hysteresis curve determine the return rate of the source.

With this design change, the drug release rate of the time andtemperature compensating drug delivery system remains constant with timeat a constant temperature but it increases as the temperature increases.The increase can be designed to be either linear or non-linear. Theincrease in release rate translates into an increase in drug strength.In the case of time and temperature integrator indicator, the mixingrate of the dye remains constant with time at constant temperature andincreases the color depth of the enclosure's fluid at a constant rate.The mixing rate of the dye increases with temperature, linearly ornon-linearly, and in return it accelerates the increase in color depthaccordingly. Additionally, the dye source, if used in the solid state,can be made up of several layers of different colors. Each layer as itis mixed with the enclosure's fluid will produce a new color that willreflect, in a more discerning way, the time and temperature history.

As shown in the embodiments of FIGS. 61, 63, and 64, both the shapememory material activator 508 and the bias spring(s) 520 can be placedin parallel with the shell, either outside or inside, respectively.

As shown in FIG. 65, the shape memory material activator spring 530 isprovided outside of the shell 502 and the bias spring 532 is providedoutside of the shell. Two additional springs are shown, including apressurant spring 534 and a compensating spring 536. The pressurantspring 534 is used to keep the liquid source under pressure in order, asmentioned above, to keep the walls of the membrane wet. Alternatively,the pressurant spring 534 can be replaced with a pressurized bladder.The compensating spring 536 is used to compensate for any increase inswelling, minimize the effects of any compression set of the sealingmeans or minimize any minor effects of any non-uniform dissolution of asolid state source.

FIG. 66 illustrates an alternative arrangement for the device of FIG. 65wherein a shape memory material activator spring 540 and a bias spring542 are provided in a central hole and the pressurant spring 544 andcompensating spring 546 are provided as in FIG. 65. Attributes for eachconcept can be combined to produce a device with more degrees of freedomand more versatility.

FIGS. 67 and 68 illustrate an alternative embodiment of a shape memorymaterial activated device 550 using leaf springs and a dome shapedclosing member. As shown in FIG. 67 a shape memory material leaf spring552 with an attached or adjacent leaf bias spring 554 can be substitutedfor the coil springs. Also, in the embodiment of FIGS. 67 and 68, thesealer 556 and the closing member 558 are in the form of dome shapedmembers.

In all the embodiments discussed herein, the closing member or the shellcan be made the moving part and the other part the stationary one simplyby exchanging places of the shape memory material and bias springs withthe compensating spring.

In all the embodiments described herein, more than one shell, containingthe same or different substances, such as drugs of various degrees ofpotency in the case of a drug delivery system, can be used with a singleenclosure. They can all be activated at the same or differenttemperatures. For shape memory materials to be activated at differenttemperatures, the chemical composition or the processing of the materialincluding the amount of deformation from the austenitic shape must bedifferent. Multiple shells will allow for several reactions/mixingsbetween the two substances to take place. As an example, in a drugdelivery system with multiple shells, shell #1 contains a drug that isto be released at a predetermined temperature while shell #2 containsthe same drug of higher potency to be released at a higher predeterminedtemperature. As a second example, if each shell contains a differentcolor dye, the fluid of the enclosure will obtain a different color ateach predetermined temperature. Each color will correspond to adifferent temperature that will be indicative of a different level ofwarning.

Additionally, the reverse shape recovery concept described earlier canbe utilized to create the path during cooling of the shape memorymaterial instead of heating. In this case, the substance will bereleased once the temperature falls below M_(s) producing the sameeffects as in the case when release takes place when the temperaturerises above A_(s). Finally, it should be understood that if the shapememory material activator is not trained in a two way shape memoryeffect or no bias spring is utilized, the path creation process will notbe reversible and once the shape recovery takes place, the shell willstay open permanently. In this case, the same effects will be producedbut would not be repeated with temperature cycling. However, if otherfeatures such as pressurization of the shell contents and variablesource concentration are maintained, the device is able to produceintegrated release with respect to time once the path is created.

Peelable Shell Systems

The devices illustrated in FIGS. 69-77 relate to the use of a shapememory material activator to peel a barrier layer away from a shellcreating a path through the shell. The peelable shell devices may beused to enhance the characteristics of the transdermal (patch) andimplant type drug delivery systems by converting them from continuousdelivery systems to “on demand” drug delivery systems. The peelableshell devices may also be used for temperature warning devices, however,these devices will be described primarily with respect to the deliveryof drugs. The operating principle of the peelable shell systems is thesame as for the temperature warning devices, the difference being thatthe shell contains a drug instead of a dye. The drug is released into areservoir that is specifically designed to transmit it to the patient.The reservoir may contain another drug, in either the solid or liquidstate, that is to be mixed with the one that is released.

For purposes of background, there are two types of transdermal drugdelivery systems, also known as patches. One that contains the drug in areservoir and releases it through a rate controlling membrane, and asecond one which contains the drug in a polymeric matrix which isapplied directly to the skin. In both cases the skin begins to absorbthe drug as soon as the protective liner is removed and the patch isadhered to the skin. The device presented herein takes the patch conceptone step further and advances it to be qualified as an on demandtransdermal drug delivery system. This is accomplished with the additionof a peelable barrier between the drug and an intermediate layer of thetransdermal drug delivery system or the drug and the skin. This layer isautomatically removed (peeled away) only, after the patch has beenapplied to the skin and only when and if there is demand for the drug.

Automatic removal of the barrier is achieved with the incorporation of ashape memory material activator in the device. Demand is determined byseveral ways. In the case of fever, the shape memory material can acteither as both a sensor to detect the rise in temperature and as anactuator to remove the barrier layer at a predetermined temperature orsimply as an actuator with the sensor being replaced with a separatetemperature detection device. In the second case, activation of theshape memory material will require an external energy source to heat itand enable it to undergo the shape recovery process. In other cases suchas cardiovascular and hormonal drugs, the shape memory material deviceis only used as an actuator with the sensing provided by addeddetectors. When detectors are used, microprocessors can also beincorporated to provide additional features to further enhance the selfcontrolled characteristics of the device.

An added feature of this system is the fact that actuation can also beachieved manually. This is accomplished with the application of heatsource such as a hot towel to the device. For this to work, thetemperature of the applied heat source must be high enough for the shapememory material activator to undergo shape recovery. On the other hand,this temperature should not be so high as to alter the nature or potencyof the drug nor should it change its ability to be absorbed by the skin.

In addition to the peelable layer, in the case of the drug reservoirtype transdermal device, the shell can be placed inside the reservoir.Release of the drug into the reservoir takes place at the predeterminedtemperature. The reservoir may contain another drug or carrier withwhich it gets mixed prior to the absorption process.

In all cases, multiple shells can be used with each device to enableincremental adjustment of the drug dosage with respect to fever or otherparameters. FIGS. 69 and 70 illustrate the basic components andoperating principle of the peelable shell device 600. For a temperaturewarning device, the device 600 utilizes the mixing of two substances toproduce a color change once the predetermined temperature of the deviceis reached. For a drug delivery device, the device 600 releases a drugfrom the shell. The device 600 consists of a shell 602 formed by a rigidor semi-rigid backing 604 and a protective liner 606. The protectiveliner 606 is attached to the backing 604 by an adhesive 608. Theprotective liner 606 is connected by a pull tab 610 to a shape memorymaterial activator 612. The shell 602 for the temperature warning deviceis positioned within or adjacent an enclosure which may contain a secondsubstance.

The peelable shell drug delivery system consists of substantially thesame components as the temperature warning device described aboveexcept, the substance delivered from the shell is a drug. The deviceincorporates a drug containing shell inside a drug reservoir. The shellencapsulates the drug to be released into the reservoir that willdeliver it to the patient as a transdermal or implanted system. Thereservoir can be either empty to receive the drug contained in the shellor filled with another drug to be mixed with the one released by theshell. The second option provides the advantage of extending a drug'sshelf life if mixing is to take place at the time of application insteadof the time of manufacturing.

Again, activation of the device 600 takes place when a shape memorymaterial activator 612 peels the protective liner 606 which creates apath through the shell 602 for the drug to be released to the reservoir.The shape memory material can be placed either in the inside or theoutside of the shell and must be compatible with the drug or be coatedwith a coating that is compatible with the drug. For transdermal systemsverification of the release can be provided through a transparent windowin the reservoir that will exhibit a color change.

As shown in the embodiments of FIGS. 69-77, the path through the shell602 is created by a peeling process. The shell 602, that may contain adye or a drug, is formed by two parts; the rigid or semi-rigid backing606 and the flexible protective liner 606 held together with theadhesive 608. With the incorporation of a shape memory materialactivator 612 the protective liner 606 is peeled away automatically oncea predetermined temperature is exceeded, thereby creating a path for thesubstance within the shell 602 to be released.

As shown in the embodiments of FIGS. 70-75, the shell can be dividedinto multiple individual shells with each shell containing the samesource such as the same drug of equal or increased strength, or adifferent drug. As the temperature increases more shells are peeledaway. With this incremental process the drug strength or color depth ofthe enclosure changes with each shell that is peeled away. Each color isindicative of exposure to a specific temperature. In the case of ondemand drug delivery systems, the drug can be released for directabsorption by a mammalian body through a rate controlling membrane or itcan be mixed with another drug prior to the absorption process. Peelingalso includes the process of removing part of the shell wall by tearingor drawing (such as pulling, pushing or rotating) whether the part ofthe wall is adhered to the shell, scribed, notched, scored, grooved orotherwise prepared for removal. In addition, it includes mechanicalunlocking (such as zipping open) of the shell.

FIG. 70 illustrates a transdermal drug delivery device 620 havingmultiple shells 622 separated by barriers 624. A peelable protectiveliner 626 is provided between the shells 622 and a rate controllingmembrane 628 and is activated by a shape memory material activator 632.An adhesive layer 630 may be used to affix the device 620 to a patient.

FIGS. 71 and 72 show a similar concept of multiple shells 642 and asingle activator 646 with each shell having its own liner 644. Thisconcept has the advantage of minimizing the overall length of the deviceand by adjusting the length of the individual tabs the temperature rangebetween peelings can be adjusted accordingly. FIG. 71 shows a device 640having multiple shells 642 connected in series with individual tabs 648of varying lengths connected in series such that the shells on a righthand side of the device are peeled first.

FIG. 72 shows a device 650 having multiple shells 652 with individualliners 654 and individual tabs 658 of varying lengths connected inparallel such that the shells on the left hand side of the device arepeeled first. With this concept, peeling of each shell is independent ofthe others in the group.

In the embodiments of FIGS. 71 and 72, the shells are peeled away atequal temperature ranges provided the movement of the shape memorymaterial spring is linear with respect to temperature. The length of theindividual tabs may be equal or unequal which results in a peelingsequence of even or uneven temperature ranges. The peeling rate withrespect to temperature can also be controlled with the width of theindividual shells. In an alternative embodiment, in which tabs areprovided of equal length, the shells are peeled simultaneously.

FIG. 73 shows a concept in which the shells are filled with a solidstate substance, such as a compacted powder of drug or dye. In a device660 of FIG. 73, the powder 662 is sandwiched between two adhesive layers664, 666 and together with the sandwiched source constitutes the shell.The adhesive layer 666 connects the shell to a backing 670. During shaperecovery the protective liner 668 on the adhesive layer 664 is peeledaway at a rate corresponding to the temperature change exposing thesubstance 662 to the fluid of the enclosure in continuous fashion. Inthis case, the substance 662 is a true source. The advantage of thissystem is the fact that different source strengths or different sourcescan be used along the length of the strip. This concept is equivalent totime-temperature dependent systems except, it is restricted to a singleone half of a temperature cycle, either A_(s) to A_(f) or M_(s) toM_(f).

The peelable shells can be arranged in different sizes and patterns toaccommodate different requirements of temperature spans, types ofsources, sequence of releases etc. In addition, the configuration of thepeelable protective liners can be varied to accommodate differentrequirements. Some of the different patterns include shells of differentwidths, shells arranged in both series and parallel fashion, and shellswith circular shaped or blister type drug containing cavities in seriesand/or parallel.

For transdermal systems the device should be designed such as to preventany deformation of the shape memory material element during handling andapplication of the patch in order not to affect its performance. It isrecognized that the patch is not applied to rigid flat surfaces and eachapplication is unique in terms of geometry. In order to avoiddeformation of the shape memory material during the application process,the shape memory material can be housed separately from the patch in arigid housing and be connected to the barrier layer with a flexibleconduit.

FIGS. 74 and 75 show an alternative embodiment of a transdermal patchdevice 680 with the shape memory material activator 682 placed on top ofthe patch. In FIG. 75, the shape memory material activator 682 haspulled the barrier 684 from two sides. However, it should be understoodthat the barrier may also be pulled from one side of the patch.

Besides the use of the coiled shape memory material spring as shown inFIGS. 69-75, the peelable shell device may include a leaf spring orother shape memory material activator to peel the liner. FIGS. 76 and 77show a peelable embodiment of a shape memory material activated device690 in which the shape memory material activator 692 is in the form of aleaf spring. The shape of the shell 694 and the peelable liner 696should accommodate the movement of the shape memory material activator692. As with the shape memory material coil spring, a multi-shellconstruction can also be used with the leaf spring. In both cases, coilspring or bent wire, shells with different geometry clustered togetherin different patterns can be used.

It should be understood that even though in all peelable conceptsdescribed herein, the path creation took place by pulling the tab of thepeelable layer while the shell remained stationary; the same can beachieved by holding the tab stationary and moving the shell by couplingit with the shape memory material. The shape memory material can eitherpush or pull the shell, depending on the orientation of the opening, tocrate the path and release the substance.

When the drug delivery device is a device of the type where the drug isprovided in a matrix the auto-peelable barrier is placed at the bottomof the matrix. An extra liner, between the peelable barrier and thematrix would help minimize the startling effects of the sudden barriermovement during shape recovery. This layer should be transparent to thedrug or contain large holes such that the most of the matrix is incontact with the skin. The matrix may be segmented and each segmenthaving its own barrier. The barriers are removed in a “curtain” fashionwith each curtain attached separately to the shape memory materialactivator. By varying the curtain length, each cell can be exposed tothe skin at different temperature. Curtains close to the fixed end ofthe spring tend to produce smaller movements which necessitates smallercells. However, by adjusting the curtain length of the individual cells,all cells can have the same size.

Another concept involves two barriers, one stationary and one mobile.Both barriers have alternating strips with cut outs of the same size.Initially, the two barriers are placed out of phase such that the drugmatrix is sealed. Upon shape recovery one of the barriers begins to moveexposing small areas of the matrix to the skin. At the end of the shaperecovery process the strips and cutouts of the two barriers are in phaseand maximum exposure is achieved.

In the peelable shell concept, the shape memory material spring is notlimited to an outside location only. It can also be placed inside theshell as well. In this case, peeling takes place inside the shell. Whenambient heat is used for activation of a peelable shell device thisconcept presents the advantages that both the shell substance and theshape memory material spring are at the same temperature at all times.This advantage exists for all the types of release devices that, containthe shape memory material inside the shell.

FIG. 78 illustrates an embodiment for releasing a substance outside of apredetermined temperature range. Release takes place either above apredefined maximum temperature or below a predefined minimumtemperature. This is achieved with a dual shell device 700 comprising ashape memory material spring 702, a bias spring 704, a lever 706 and twopeelable shells 708. The peelable layers of the two shells 708 areconnected to the lever 706 that is joined to the two springs 702 and 704at their interface. The lever is free to travel as the interface of thetwo springs shifts with temperature cycling. When the shape memorymaterial spring undergoes shape recovery and changes length, theinterface between the two springs, along with the lever, move in onedirection and create a path to release the substance. The path iscreated in the shell that the lever travels way from by pulling thepeelable layer away. When it undergoes reverse shape recovery withtemperature reversal, the bias spring moves the lever in the oppositedirection such that it pulls the tab of the second shell and creates thepath to release the substance. When the device is placed in service, thetemperature of the shape memory material spring must be within thehysteresis temperature width. The temperature range within which releasewill not take place is defined by the width of the hysteresis curve.This concept is not limited to peelable shells only; it can be extendedto other shells as well.

An added benefit to peelable shell concept is that besides being a shellcapable of releasing a substance, it can also become a temperatureindicator without the aid of the released substance. This is achieved bymarking or bonding a calibrated temperature strip indicator on theunderside of the peelable layer. As this layer is peeled away duringshape recovery, the underside is exposed and the temperature stripbecomes visible. The highest exposure temperature, if shape recovery isused to create the path, is indicated right at the folding line formedby the peeled portion and the unpeeled portion. This concept can beextended to a peelable temperature indicator without the shell. This isachieved by peeling a layer that is bonded to a substrate that containsa temperature strip indicator. Once the shape recovery begins and thepeeling starts, the temperature indicator is exposed continuously withincreasing temperature. The latest exposed part is the one correspondingto either the highest or lowest temperature depending whether peelingtakes place with rising or falling temperature.

A concept similar to the peelable shell is the sliding cover shell. Inthis concept, the path to release the substance contained inside theshell is created by the moving of a cover away from a window by asliding action. The cover may be adhered to the shell and form part ofthe shell wall. Adhesion can be accomplished by several methods such asbonding, welding, pressure differential, contact stresses, or Van DerWall forces. Heavy covers may be held in place by gravity without theaid of any adhesion. The cover in turn is connected to the shape memorymaterial spring. Upon shape recovery, the shape memory material springpulls, pushes or otherwise moves the cover away from the window torelease or admit the substance.

Release Rate Control

In all shells described herein, irrespective of how the path is created,a porous barrier such as permeable or semi-permeable membrane may beincorporated between the inside surface of the shell and the substancecontained inside the shell. One purpose of this material is to controlthe transfer rate of the substance as it exits or enters the shell oncethe path through the shell wall has been created. Another purpose is tocontrol the part of the substance to be released or admitted. An exampleof this is the release of the volatile part of a substance, in whichcase the membrane provides the path for the volatile compounds to bereleased but acts as a barrier to keep the remaining substance insidethe shell. A third purpose includes release of a specific substance,among multiple substances contained in the shell, that has theproperties to allow it to travel through the membrane. The release rateis mostly controlled by the permeability characteristics of the materialand the prevailing pressure differential between the inside contents andthe surrounding environment. Pressure differential is achieved with theincorporation of pressurant means to create and maintain a pressuredifference for the substances to be released or admitted. Pressurantmeans may include any of the volume changing devices described hereinand the like. In addition, the incorporation of absorptive means insidethe shell, such as polymeric matrices, would provide further control bypreventing instantaneous release or absorption and stabilizing theexistence of any differential pressure. The permeable material can be inthe form of a membrane, a coating, film, layer, mesh, screen, strainer,filter etc. Choice of material and design depend on substance to bereleased or admitted and the desired transfer rate of the substance.

The permeable material can encapsulate the entire substance when thelocation of the path is indetermined or it can be placed strategicallyin the location where it is known that the path will be created(predetermined path). Strategic locations are places like the peelablelayer of a shell, where the permeable material will provide rate controlonce the peelable layer is removed. The permeable material may have tobe flexible to accommodate any volume changes during the path creationrelease processes. Further, this jacketing material may not be permeableon its entire surface. By being part permeable and part impermeable, itprovides one more degree of freedom to control the transfer or releaserate by adjusting the ratio of permeable to impermeable area. Thisconcept of jacketing the substance with a permeable or semi-permeablebarrier such as a membrane can be extended to all concepts of releasedevices presented herein irrespective of how the path is created. FIG.79 illustrates an example of a shape memory material activated device720 comprising an enclosure 724 housing a shape memory material spring722 and a shell 726 containing a substance that is encapsulated by apermeable layer 728. When the shape memory material spring 722 undergoesshape recovery, it stretches the shell 726 to create single or multiplepaths through which to release the substance. Irrespective of the pathtype and size (microscopic or macroscopic), the substance is releasedthrough these wall paths at a rate controlled by the permeable layer728.

Additionally, the path size or rate of exposed area covering thesubstance can vary with temperature, This can be accomplished with apeelable shell having a pull-away tab that that becomes progressivelywider. As the path creation process begins, a small opening is createdto release the substance through a permeable layer. As the path creationprocess continues with increased temperature, the opening, in additionto becoming longer, also becomes progressively wider, allowing for avariable release rate. As the release rate depends on the exposed area,by varying the geometry of the peelable layer, a relationship betweentemperature and release rate can be established. With this concept, therelease rate will stay constant with time but will vary withtemperature.

One more degree of freedom of controlling the release rate can beprovided by progressively varying the amount of porosity or degree ofpermeability of the jacketing layer along the path length. The variationcan be continuous or incremental. With this concept, the permeability,and therefore the release rate, can increase or decrease with changes intemperature.

Based on the above, there are several ways to control the release rateof the substance and to produce either a constant or a variable rate:(a) wrap the substance with a permeable layer of either constant orvariable permeability (b) wrap the substance with a barrier layer thatis permeable only in selective areas (c) design the rate of the pathopening area to be linear or non-linear with respect to temperature (d)incorporate pressurant means inside or outside the shell.

An alternative placement of the rate control material is outside of theshell to encapsulate the whole device such that all components,including the shell and the shape memory material, are inside. Thisconcept provides the choice of jacketing the same devices with differentrate control material to achieve different release rates. In this case,the jacketing material effectively becomes a reservoir that controls therelease rate of the substance to the surroundings.

Release Mechanisms

The following description relates to shape memory material activatedrelease mechanisms, such as described above with respect to FIG. 4. Itshould be understood that the combination of a non-shape memory materialmechanical element and a shape memory material release mechanism may beused in place of a shape memory material spring in any of theembodiments described above.

In addition to the embodiments described above, a release mechanism canalso be used in the impact shell devices shown in FIGS. 80-83. Theseembodiments allow for rapid path creation through instantaneous releaseof stored energy, resulting in more precise temperature control.

FIG. 80 illustrates a shape memory activated device 800 including ashell 802 and an elastically deformed spring member 804 (such as a wireor strip) to store the energy required to fracture the shell. The spring804 can be made of either superelastic material or regular springmaterial. The spring 804 is kept in the bent position with two tensionwires 806 (or rods) connected with a release mechanism 808. FIG. 80,shows the shell 802 being loosely suspended between the two ends of thespring 804 with two wires 806 or rods. The loose suspension conceptallows the spring to move the distance x and prevents minor forces,generated from A₁ to the release temperature, from being transferred tothe shell and creating the path prematurely. In addition, it allows thereleased spring 804 to obtain momentum before it creates the path byfracturing, exploding, imploding, puncturing, peeling, tearing,shearing, rupturing, splitting, separating, debonding, delaminating etc.the shell 802.

As shown in FIG. 81, the shell 802 may also be positioned in line withthe release mechanism 808 along the wires 806 in the device 800.

As shown in FIG. 82, besides being suspended, the shell 802 can also bean integral part of and surround the bent spring 804 in the device 800.The shell path in the first case is created by tension or shear(depending on shell construction) whereas the second case is created bybending.

Several types of release mechanisms can be employed with this concept.The type depends on temperature-release precision required, spaceavailability, design flexibility, compatibility, ease of path creationetc. Different types of release mechanisms are discussed with respect toFIGS. 84-88. Additional examples of release mechanisms are described inU.S. Provisional Patent Application Ser. No. 60/191,703 which isincorporated herein by reference in its entirety.

FIG. 83 illustrates an impact device 850 in which a compressed coilspring 852 is used to cause the shell 854 to be impacted. Impact isinitiated by the release device 858 which releases the tension wire (orrod) 860 and in turn allows the spring 852 which is held undercompression between two plates 856 to impact the shell 854. In adifferent configuration, either or both the shell and the release devicecan be placed inside the spring. When the shell is placed inside thespring, upon impact the shell is pulled apart in tension as it is tiedto both ends of the spring.

A series of concepts for release mechanisms to be used in conjunctionwith any of the embodiments described herein are described withreference to FIGS. 84-88. Their purpose is to release the storedmechanical energy instantaneously, produce a maximum impact on the shelland improve activation accuracy of the device. The mechanism is insertedbetween the shape memory material, which activates the mechanism, andthe shell that receives the released energy. The incorporation of therelease mechanism eliminates the slow application of force by the shapememory material itself during the martensitic to austenitic phasetransformation.

FIG. 84 illustrates a release mechanism 900 which utilizes a body withtwo hemispherical cavities 902 that are used as sockets for ball joints904. One ball joint, illustrated in detail in FIGS. 84B, 84C, and 84D isdesigned with slots such that when the slots of the cavity and the ball(cup in this case) are lined up, the joint is separated, therebyreleasing the load. The line up of the cavity and the cup is achievedthrough the rotation of the body by two shape memory material springs906 attached to pivoted paddles 908. The springs 906 work as a couple torotate the body 910, as shown in FIG. 84A. The springs 906 are bent inthe martensitic state and become straight in the austenitic state.During the transformation process the springs 906 rotate the body 910and, when the slots of the cavity and the cup are lined up (FIG. 84D),the restrained spring is released. Depending on the size of themechanism and the amount of stored energy, one shape memory materialspring 906 may be utilized. The friction between the cavity and the cupmust be minimized to the point that no rotation is transferred to thecup. If the cup tends to rotate, the rod attached to the cup must beintegral with the cup and provisions must be made to restrain it fromrotating. For clarity, two slots are shown in the hemispherical cavities902 and 904 of FIG. 84B. For optimum performance, four or more slots maybe incorporated.

To allow for the case where the temperature rises above A_(s) and dropsto below A_(s) before it reaches A_(f) and release is not achieved, abias spring 920 attached to posts 922 is incorporated in the embodimentof FIGS. 85 and 85A. The purpose of the bias spring 920 is to return thebody 910 back to its original position. This will eliminate thepossibility of accidental release though impact in the case where theslots are close to the release position and the temperature drops. Forthis concept to work, the shape memory material should be trained toachieve a two way shape memory effect. Without the two way shape memoryeffect, an additional bias spring 924 integral with or connected to theshape memory material spring 906 should be used. The first bias springrotates the body back to its original position and the second aids thereturn of the shape memory material to its original shape.

FIGS. 86 and 87 illustrate an instantaneous pin puller release mechanism950. The pin puller 950 is used to release a single tension member.Unlike the previous release mechanisms, this one employs a shape memorymaterial coil spring 952 to pull a pin 954 and separate two halves 956,958. A bias coil spring can be used coaxially with the shape memorymaterial spring 952 to return the spring to its original position whenthe phase transformation is incomplete and no release takes place. Thereis less of a need for a bias spring in this case since accidentallyinduced impact forces are not likely to release the hinge member. Oneadvantage of this design is the elimination of the need to anchor themechanism as no force couples are generated.

FIG. 88 illustrates a force limited release system 960. This conceptallows a shape memory material element 962 to be released when itdevelops a certain amount of resistance force against an object 964 suchas a restraining leaf spring. As the temperature is increased aboveA_(s), the shape memory material element 962 applies an increased forceagainst the restraining spring 964, which in turn begins to deflect andcreates more room for the shape memory material element to be released.By controlling the properties, shape and size of the restraining spring964 for a given shape memory material element 962, the releasetemperature within the A_(s) to A_(f) range can be controlled. If thetransformation cycle is not completed and no release takes place, theleaf spring 964 returns the shape memory material element 962 back toits original position. To aid the release process and minimize thepossibility of binding, sleeves can be added to the shape memorymaterial element such that the sleeve is in contact with the restrainingspring.

When mechanisms as the ones described above (that release storedmechanical energy to activate the device) are used to release a drug, anauditory signal is emitted, the strength of which depends on factorssuch as material of construction and medium the signal has to travel.This property becomes significant for implants where a manual adjustmentof a drug dosage can be detected with device such as a stethoscope. Thisprovides assurance of the drug release and eliminates the uncertainty orthe requirement for radiography. Other means for producing auditorysignals include pressure difference between shell contents andsurroundings, shells with brittle walls and shape recovery with a narrowtemperature range that results in an accelerated path creation process.

Thermally Activated Transporter

The device illustrated in FIG. 89 is a self-propelled thermally powereddevice driven by a shape memory material activator that, when subjectedto temperature cycling, converts thermal energy into mechanical energyand in the process performs multiple functions. Typically, thesefunctions combine motion with force and they can be performed eithersequentially or simultaneously with temperature change of shape memorymaterial actuator. They include, but are not limited to, travel from onelocation to another, transportation of a load, release of a substance,expansion of conduits, and actuation and powering of other devices. Theconcept on which this device is based is similar to the ones presentedearlier for shape memory material activated pressure generators.

When the thermally powered device is left unrestrained, it becomes aself-propelled vehicle that can travel on guided single or multipletracks, or unguided in different media and on surfaces. The device iscapable of traveling on any track, medium or surface, including flatsurfaces, that will allow forward movement but will provide traction toprevent reverse movement. The device moves by first thrusting one endforward during the first half of the temperature cycle while the secondend provides traction, then, thrusting the second end forward during thesecond half of the temperature cycle while the first end providestraction. With this sequential movement of the two ends the deviceexpands and contracts with temperature cycling. The order of expansionand contraction with respect to temperature change is determined by thedirection of the shape recovery of the shape memory material activator.

FIG. 89 illustrates a thermally powered device 1,000 comprising a shapememory material spring 1,002, a bias spring 1,004 and a variable lengthbody 1,006 with a plurality of fins 1,008. The fins 1,008 are workenablers that allow the thermally powered device 1,000 to interact withits environment and to perform work. They provide the necessary tractionmeans to prevent reverse movement and at the same time facilitate theforward movement. Reversal of travel is prevented by the locking actionproduced by frictional or traction means. In addition, the work enablersprovide stability and aid the direction of travel. The configuration ofthe work enablers is determined by their functional environment and thetype of travel they have to perform such as traveling on a track, on aflat surface or in a specific medium such as a viscous substance orparticulate media. In addition, the fins may be configured for nontravel functions such as the actuation or activation of a mechanism. Thework enablers can be comprised of single or multiple parts configuredwith flat, cylindrical, conical, spherical, or a combination thereof ofgeometric features constructed of rigid, flexible or compressiblematerials. As an example, the forward surface of the work enablers maybe made of a non-absorbent material while the aft side is made of anabsorbent material. During one half of the temperature cycle, the aftside absorbs the surrounding fluid, becomes stiffer and providesincreased traction. During the second half, the work enablers flextowards the body of the device, compress their aft sides against it, andsqueezed out the fluid. In addition, the work enablers may be sculptedon the surface of the variable length body to form either depressionssuch as dents, dimples and cavities or protrusions. In the first case,the work enablers are inwardly projecting and in the second one they areoutwardly projecting. Some of the configurations for the work enablersinclude; fins to enable travel on tracks containing similar fins,detents to enable travel on a ratchet gear system, fins with specialsurface features to enable travel in viscous fluids or particulatemedia, and wheels that prevent reverse rotation to enable travel on aflat surface or inside a hollow track. Depending on the type of travel,each of the work enablers may be continuous around the circumference ofthe variable length body 1,006, or may constitute a circumferentialsegment. As an example, for a round type variable length body, unguidedsurface travel can be achieved with conical type work enablers, segmentsof conical work enablers or just wire extensions. Continuous orsegmented work enablers placed around the variable length body allow thedevice to rotate or tumble while traveling and make travel orientationfree with respect to the placement of the work enablers. The fins 1,008can be either integral or attached to the variable length body 1,006.They can be attached such as to be fixed or they can be pivoted to allowfor an adjustable width span to accommodate travel in variable widthtracks such as tubes of changing diameter or variable roundness.Generally, the work enablers are preferentially oriented with respect tothe direction of travel to provide minimal resistance to forwardmovement and maximum resistance to backward movement. This is achievedby biasing them such that the aft angle formed between the work enablersand the direction of travel is an acute angle. In addition to multipleconfigurations of the work enablers, the variable length body can havemultiple configurations as well. It can be of any shape that wouldpermit the attachment of the work enablers and will not inhibit thelength variability. In addition, its cross section may change from oneend to the other to accommodate the travel requirements.

The bias spring 1,004 can be eliminated if the variable length body1,006 is also used as spring or if the shape memory material spring1,002 is trained in a two way shape memory effect. Further, the variablelength body itself can become the shape memory material spring 1,002trained in a two way shape memory. In addition, the variable length body1,006 can be eliminated if the work enables are attached directly to theshape memory material spring 1,002 or the bias spring 1,004. In certainapplications, the shape memory material spring or the bias spring mayperform the function of the work enablers and as such, the need for thevariable length body is eliminated. Further, multiple shape memorymaterial springs with the same hysteresis curves, coupled with biassprings, may be incorporated. Multiple springs with reduced crosssections allow for faster heating and cooling. In addition, they allowfor the thermally powered device to travel on a curvilinear path. If twosets of shape memory material springs of unequal length coupled withcompatible lengths bias springs are placed inside a variable length bodyin diametrically opposite locations, the longer shape memory materialspring would produce a larger expansion, comparing to the shorter one,and force the thermally powered device to travel on a curved path.Depending on the configuration of the shape memory material and thetravel environment, there are times that work enablers are not required.A case for this would be a thermally powered device comprised of shapememory material activator that is configured aerodynamically to minimizethe forward resistance and maximize the backward resistance. A similarcase exists when the device is traveling in a medium of decreasingdensity where there is less resistance to forward movement and a higherresistance to backward movement. Depending on the prevailing conditionsand the design of the device, a slight backward movement may betolerated but the net effect is a forward movement with each fulltemperature cycle.

FIGS. 90, 91 and 92 illustrate an example of a shape memory materialactivated transport device 1,020 utilizing the thermally powered device1,000 traveling on a plurality of tracks 1,022, each configured with aplurality of track fins 1,024. The fins 1008 of the variable length body1,006 and the track fins 1,024 are oriented in the same direction, andare substantially flexible to allow movement of the variable length bodyin one direction but prevent the reverse movement by a locking action.The orientation of the fins is such that the variable length body finsare inclined toward the opposite direction of travel, while the trackfins are inclined toward the travel direction with both sets essentiallybeing parallel to each other. The shape memory material spring 1,002 andthe bias spring 1,004 are housed inside the variable length body 1,006.As the temperature of the shape memory material spring 1,002 rises, itgoes through shape recovery, overcomes the resistance offered by thebias spring 1,004 and in the process of expanding, forces the variablelength body 1,006 to expand in one direction. FIG. 90 illustrates theembodiment of the shape memory material activated transport device 1,020with the shape memory material spring 1,022 in the deformed martensiticstate. FIG. 91 illustrates the forward advancement of the forward end ofthe thermally powered device 1,000 on the tracks. When the shape memorymaterial spring 1,002 is heated above A_(s) it undergoes shape recovery,overcomes the resistance force of the bias spring 1,004 and, as itexpands, it increases the length of the variable length body 1,006. Thelength increase is prevented from taking place in the backward directionby the locking action of the biased fins while it is allowed in theforward direction. As the variable length body increases in length, thefins move past each other and accommodate each other by flexing towardtheir respective attachment points. They flex back to their originalshape once they move past each other and they are no longer in contactwith each other. FIG. 92 illustrates the forward advancement of the aftend of the thermally powered device 1,000 on the tracks. When the shapememory material spring 1,002 undergoes reverse recovery, the bias spring1,004 forces the variable length body 1,006 to contract in length.During this half of the temperature cycle, by a similar locking andflexing action of the fins, the forward end is prevented from movingbackward while the aft end is allowed to move forward. This movementallows the variable length body to return to is initial size at thecompletion of the temperature cycle. The interaction of the workenablers, fins in this case, provide the necessary traction means forthe forward advancement of the thermally powered device. The spacing ofthe work enablers on both the track and the thermally powered devicedetermine the precision of travel. With each half of the temperaturecycle, the work enablers along the length of the thermally powereddevice move progressively from zero to the full distance of travel. Bydecreasing the spacing of the work enablers on the track side allows forbetter gripping as more work enables from both sides are able to mesh.The spacing of the work enablers does not have to be uniform. In can berandom as in the case when irregular surface morphology is used as meansfor traction.

With the sequential advancement of one end followed by the other end,the thermally powered device 1,000, in one temperature cycle, travels adistance equal to the displacement produced by the shape memory materialspring 1,002 in one half of the cycle. This way, the device is capableof traveling continuously with temperature cycling of the shape memorymaterial spring. As a traveling vehicle, it is capable of performingmultiple tasks. A few of these tasks are; carry a load from one locationto another (in essence becoming a thermally activated transporter),release a substance along the travel path or at selected locations, pushor pull on object, expand a tube or an opening, place on object at aspecific location and, trigger an action as to activate a device byturning on a switch. The travel distance can be measured in wholetemperature cycles or degrees of temperature per unit distance.

FIGS. 93 and 94 illustrate examples of a shape memory material activatedtransport devices 1,030 and 1,040, respectively. They are similar to theone illustrated in FIG. 90, but with the thermally powered devicesutilizing a lower number of parts. The thermally powered device 1,038 ofFIG. 93 consists of a shape memory material spring 1,032 in the form ofa convoluted sheet or foil embedded in an elastomeric type material1,034, configured with integral fins, that acts as a bias spring therebyeliminating the need for a variable length body. The shape memorymaterial spring 1,032 has a convoluted shape in the martensitic stateand assumes a straight shape upon shape recovery and in the processstretches the elastomeric bias spring. The fins of both the thermallypowered device and of the track 1,036 have sufficient flexibility toallow the thermally powered device to advance in one direction butprevent it from moving in the opposite direction. When of a shape memorymaterial spring in a convoluted shape is used, the track mustaccommodate any waviness in the elastomeric material caused by the shaperecovery process. The waviness is caused by the fact that when the shapememory material obtains a straight shape, the elastomeric materialcontained in the concave side of each convolute is deformed elasticallyand bulges out. The bulging alternates between sides and follows theorientation of the convolutes resulting in a waviness along the lengthof the thermally powered device. The degree of waviness is influencedmostly by the radius and the arc length of the convolutes and thegeneral shape of the elastomeric material. For an elastomeric materialof constant thickness that resembles the shape of the shape memorymaterial, the waviness decreases with the straightening of the shapememory material. With increased waviness, the thermally powered deviceforces the width or opening of the track to increase. This forcedincrease in the track opening provides opportunities for severalapplications that are described further below. The thermally powereddevice 1,040 is shown in FIG. 94 an axial cross sectional view. Thedevice 1,040 consists of a shape memory material spring 1,042 trained intwo way shape memory effect and configured with integral fins. This is asingle part thermally powered device that travels on the outside surfaceof hollow tubular track 1,044 configured with fins. As the shape memorymaterial spring 1,042 expands and contracts with temperature cycling, itadvances forward similarly to the thermally powered devices illustratedin FIGS. 90 and 93.

FIG. 95 shows an alternative embodiment of a shape memory materialactivated transport device 1,060 utilizing a modified thermally powereddevice 1050. The device 1050 has a hollow variable length body 1,056configured with a plurality of internal fins 1,058 and containing ashape memory material spring 1,052 coupled with a bias spring 1,054. Thefins 1,058 facilitate the riding of device 1,050 on an internal“monorail” type single track guide rod 1,062 configured with a pluralityof teeth 1,064 to allow travel in one direction only. The deviceoperates the same way as the one illustrated in FIG. 90, with one end ofthe modified thermally powered device 1,050 advancing during the firsthalf of the temperature cycle and the other end during the second half.The guide rod can also be a cylinder configured with fins or otherfrictional means as work enablers instead of teeth. Also, multipleinternal tracks can be used instead of a single track. One advantage ofthe internal track is that is has a small profile and can be easilyinserted in small tubes, body cavities or blood vessels and follow atreacherous path to guide the thermally powered device through it.

FIG. 96 illustrates an embodiment of a shape memory material activatedcircular transport device 1,100 comprising a circular outer track 1,110configured with a plurality of inward fins 1,112, a circular inner track1,114 configured with a plurality of outward fins 1,116 and a circularthermally powered device 1,120. The circular thermally powered device1,120 comprises a curved variable length body 1,106 with a plurality offins 1,108 that houses a shape memory material spring 1,102, and a biasspring 1,104. The fins 1108 of the variable length body 1,006 and thoseof the outer 1,112 and inner track 1,114 are skewed such as to allowmovement of the variable length body in one circumferential directionbut prevent the reverse movement by a locking action. During temperaturecycling, the curved variable length body 1,106 expands and contractswhile maintaining its curvature, thereby allowing the thermally powereddevice 1,120 to travel on a closed circular loop defined by the twotracks. The circular tracks may be comprised of a set of coaxialcylinders or simply a tube formed as a toroid that houses the thermallypowered device. In the first case, the fins may be skewed and flat andin the second case, they may resemble conical surfaces. In both cases,they may be configured with additional features such as slots andvariable thickness to increase their flexibility and to facilitate thetravel process.

The thermally powered device is capable of traveling on any two or threedimensional, open or closed loop, guided or unguided path. To avoidkinking of the shape memory material 1,132 and the bias 1,134 springs,they can be housed in telescoping tubes formed in circular segments asillustrated in FIG. 97. The outer 1,136 and the inner 1,138 tubes can berigid to conform to a path of constant radius or flexible to providinglateral support and accommodate variable curvature paths. In addition,if the telescoping tubes are configured with work enablers such as finsthat do not impede the expansion and contraction process, they can beused as a variable length body. Generally, the minimum number of finsrequired for any variable length body, including telescoping tubes, isone set of fins at each end of the variable length body.

FIGS. 98 to 100 illustrate an embodiment of a shape memory materialactivated transport device 1,150 with a thermally powered device 1,160traveling on wheels. The thermally powered device 1,160 is similar todevice 1,000 illustrated in FIG. 89 but utilizes a plurality of wheels1,162 attached to the variable length body with struts 1,162 instead offins. The wheels 1,162 rotate only in one direction to prevent backwardmovement. Reverse rotation is prevented with detent and ratchet gearsystems and the like. The struts can be single, rigid or flexible partsor multi-link spring-loaded assemblies that provide sufficient tensionto hold the thermally powered device on the track, prevent backwardsliding, and allow for travel on variable width tracks. Multi-part strutassemblies may allow for angular movement amongst their different partsto effectively render variable length to the struts. Variable lengthstruts increase the agility of the thermally powered devices by allowingthem to travel on variable size tracks. FIG. 98 illustrates the shapememory material activated transport device 1,150 with the shape memorymaterial spring 1,152 in the deformed martensitic state. FIG. 99illustrates the advancement of the forward end of the thermally powereddevice 1,160 during shape recovery of the shape memory material spring1,152. During the shape recovery process the variable length body 1,156increases in length in one direction. The length increase in onedirection is afforded by the wheels 1,162 that can rotate only in onedirection. The front wheels rotate to accommodate the length increasewhile the back wheels remain locked and prevent any length increase inthe opposite direction. Friction between the wheel surface and the trackprevents any movement by backward sliding. Depending on the applicationand the prevailing frictional conditions between the two surfaces, minorbackward movement may be tolerated provided that there is a net forwardmovement with each full temperature cycle. FIG. 100 illustrates theforward advancement of the aft end of the thermally powered device1,160. When the shape memory material spring 1,152 undergoes reverserecovery, the bias spring 1,154 shrinks the variable length body 1,156.During reverse recovery, the front wheels lock and prevent backwardmovement, the back wheels rotate to accommodate the shrinkage and toreturn the variable length body to its initial size, but in a newlocation.

Any type of work enablers such as fins, indentations, depressions,wheels, gear teeth, or spikes will advance the thermally powered deviceif matched it with the right track. The track provides the guiding pathand can be comprised of a tube, two parallel surfaces, single ormultiple rails, or a flat surface and the like. Also, fastener threads,male or female, can be used as a track for the thermally powered deviceto travel on. The ability to travel inside threaded holes providesopportunity for several applications such as plugging holes and securingfasteners in place.

Applications of the shape memory material activated transport devicesvary from toys to medical and industrial products to scientificinstruments. One application is the release of a substance within apredetermined temperature range, while the temperature is either risingor falling, such that each release takes place at a different locationalong the traveled course. The release is independent of time as thereis no release if the temperature stays constant. FIG. 101 shows a shapememory material activated transport device 1,200 where the thermallypowered device 1,220 performs the dual function of a transporter and ofa substance release device. The device 1,220 comprises a shell 1,206,also functioning as a variable length body, that houses a shape memorymaterial spring 1,202, a bias spring 1,204, an inward one-way flow valve1,212 and an outward one-way flow valve 1,214, and has a supplyreservoir 1,210 containing a pressurant housing 1,208 attached to it.The device 1,220 carries its own supply reservoir as it travels. Thepressurant housing 1,208 can contain a compressed fluid, a compressedspring such as one made of superelastic material, and the like whosefunction is to keep the substance contained in the reservoir underconstant pressure. Pressurization is needed only in the cases where thereservoir substance is not pressurized by the surroundings. As thevariable length body 1,206 expands, the forward end advances forward andat the same time it refills itself through the inward one-way flow valve1,212. During cooling, the variable length body 1,206 contacts, the aftend advances forward, pressurizes the substance contained inside it andcreates a path through the outward one-way flow valve 1,214 to releasethe substance. The release path can be a valve, a permeable wall orother means that will allow the substance to exit while under pressure.

FIG. 102 illustrates a concept of a shape memory material activatedtransport device 1,250 comprising a thermally powered device 1,258 thatis similar to device 1,000 of FIG. 89, a set of tracks 1,254 eachconfigured with a plurality of track fins 1,256 and a plurality ofshells 1,252 containing a substance. The shells 1,252 are located alongthe path of the thermally powered device 1,258. They are placedstrategically between the track fins such that as the thermally powereddevice advances, its fins compress the shells and create paths for thesubstances to be released. The paths through the shell walls can be inthe form of permanent physical openings such as fractures andseparations, or they can be microporous type paths. If the substance,instead of been encapsulated by the shells, is adhered to the track'sfins in a granular form, the thermally powered device can release it tothe environment by scarping it off while advancing forward. In thiscase, the track fins constitute the shells holding the substance inplace. Further, the released substance may be in multiple states ofmatter such as a liquid or a gas contained in solid state casings.

In addition to integrating shells on the fins of the tracks, the fins ofthe thermally powered device can be made progressively longer, fromfront to back, such that the shells are increasingly squeezed as thethermally powered device goes by. With this concept, all fins contributeto the release of the substance both during the heating and the coolingof the shape memory material activator. Other fin modifications mayinclude progressive adjustment of the fin angles and incorporation ofvariable stiffness fins. Further, the paths created through the wall ofthe shells may be through valves or permeable walls and the shells maybe connected to supply reservoirs. Connecting the shells to supplyreservoirs enhances the capabilities of the circular transport byenabling it to release one or more substances continuously as thethermally powered device travels around a loop. In another concept, thetrack fins can act as valves to create multiple paths and release asubstance. In this case, the deflection of the fins caused by theadvancement of the thermally powered device can create paths to releasesingle or multiple substances by opening up valves connected to supplyreservoirs.

FIG. 103 shows an example of a device 1,290 that uses a thermallypowered device 1,292, that is similar to the device 1,000 illustrated inFIG. 89, with a pointed nose 1,294 mounted to the forward advancing end.By placing a series of balloon type shells inside the tracks, releasepaths can be created sequentially in shell after shell as each shellencounters the pointed nose 1,294 of the advancing thermally powereddevice 1,292. This concept has the advantage that each release isinstantaneous and can be of a different substance. Instead of balloontype shells, other shells such as peelables can be used such that thethermally powered device can be equipped with hooks to grab their tabsas it goes by and peel them to release their substance.

FIG. 104 illustrates an embodiment of a device 1,300 that combines ashape memory material activated transport device 1,310 with a timedependent release system 1,302 that is similar to the one illustrated inFIG. 61. In this case, the operation of the time dependent releasesystem 1,302 is taken over by the thermally powered device 1,308. Thesource of the shell is attached to the forward end of thermally powereddevice 1,308 through a source bracket 1,304 and the sealer part of theshell is attached to the aft end through a sealer bracket 1,306. As theshape memory material spring undergoes shape recovery, FIG. 105, theforward end of the thermally powered device 1,308 advances forward and,in the process, pulls the source part with it, thereby creating a pathfor the substance to be released. The back end remains stationary andholds the sealer in its original position. During reverse shaperecovery, FIG. 106, the forward end remains stationary and the aft endadvances forward pulling the sealer part with it and closes the pathonce the martensitic temperature is reached. With this concept, theopening of the shell can be controlled by attaching the brackets holdingthe shell parts at different points along the length of the thermallypowered device 1,308. As an example, by attaching the sealer bracket atthe mid-point of the thermally powered device 1,308, the opening will behalf as much as it is when both parts are attached to the ends of theshell. One of the advantages of this concept is the continuous releaseand integration of substance while the shell is advancing. The releasepath is fully closed while the shape memory material spring remains inthe martensitic state. The same objective can be accomplished with theshape memory material spring contracting during shape recovery by simplyreversing the order of the attachment points. Also, the path can becreated during cooling of the shape memory material spring if the shellis closed at the austenitic temperature. In the latter case, theembodiment in FIG. 103 illustrates the austenitic condition with theshape memory material spring contracting during cooling. In this case,the release path is fully closed while the shape memory material springremains in the austenitic state. An alternative way to mount the timedependent release system 1,302 to the thermally powered device 1,308 isto house it inside. In cases where an open track system is utilized, thetime dependant system can travel outside the tracks while controlled bythe traveling thermally powered device.

Besides releasing a substance, the thermally powered device can performother functions such as pushing or pulling an object to a predefineddistance. This can be performed with the thermally powered deviceremaining on the tracks, extending a part out or using an extension arm.Applications for this concept include location identification andpositioning of medical devices. One example is the placement ofthermoseeds (magnetic rods) for the treatment of certain cancers.Anchoring the tracks in a mammalian body and utilizing the thermallypowered device as a transporter for drug or medical delivery devicesallows for a multitude of applications in the medical field. Thethermally powered device can be used as means for the transfer ordelivery of various objects, substances and the like. As an example, itmay transport a shell containing a substance to a specific location tobe released at a predetermined temperature or upon delivery. FIG. 107shows a concept of a device 1,350 having a shape memory materialactivated transport device 1,352 holding an element 1,356 at the end ofan extension arm 1,354. The element 1,356 may have any number orconfigurations of a single part or an assembly such as a tube, cable,fiber optic, medical or other device. In addition, it may be configuredwith work enablers. Once the thermally powered device advancessufficiently with thermal cycling, it can install or place the element1,356 to different destinations such as an electrical terminal toprovide an electric path, a fiber optic line to provide a light path,and terminals to provide an electric path. Further, it can be used tomechanically lock/unlock or to engage/disengage mechanical members suchas fasteners, plugs, or quick disconnects. The shape memory materialactivated transport device or the thermally powered device alone can beused to create paths in all the shells presented herein. Depending onthe nature of the element 1,356, any function requiring the applicationof a force such as assembly or disassembly, opening or closing can beaccomplished with either the shape memory material activated transportdevice or the thermally powered device alone. Besides mounting theelement 1,356 at the advancing end, it can be placed at the retreatingend. In this case, it may be utilized to pull a tab to open a path torelease a substance from a peelable shell or alternatively to create thepath by pulling a plug from a different shell. In addition, it may beutilized to disconnect or deactivate a device by pulling a criticalcomponent such as a switch or a connector.

Means such as the element 1,356 and the extension arm 1,354 can be usedto connect several thermally powered devices in series. With thisarrangement, the shape memory material spring in each device can have adifferent hysteresis curve such that at least one device is changinglength with a change in temperature within a given range. If the frontend of this particular device is advancing forward; all devices ahead ofit will be pushed forward without having to change their lengths. If onthe other hand, the back end of this particular device is advancingforward, all devices behind it will be pulled forward without having tochange their lengths. Thermally powered devices can be connected to eachother with various methods such as pin or ball joints to accommodatetravel on curved tracks and variable opening passages. In the case ofthe thermally powered devices, the sequence of activation depends on thearrangement of the hysteresis curves relative to the change in ambientheating. When the shape memory material springs are heated individuallyby external means such electric heating, a specific powering sequencecan be achieved. Advantages of connecting several thermally powereddevices in series include increase in the operating temperature range ofthe overall system and increased flexibility that allows travel alongcurved paths.

FIG. 108 shows an example where the shape memory material activatedtransport device 1,350, illustrated in FIG. 107, is utilized to releasea substance once the element 1,356 contacts a shell 1,360 placed at theend of the track. Contact takes place after the element 1,356 advancesforward with temperature cycling. Release of the substance takes bypressurization of the shell 1,360 by the element 1,356. As the thermallypowered device attempts to advance forward, when forced by the shapememory material spring, its progress is impeded by shell 1,360. Theforward advancement compresses the shell and forces it to create a pathand to release the substance. In this case the path is created through apermeable wall 1,362. The advantage of using a shape memory materialactivated transport device to release a substance is that the substancecan be released after a predetermined number of temperature cycles ofthe shape memory material activator. Each cycle corresponds to a givendistance traveled by the element 1,356. By knowing the required numberof cycles, the total distance that the element 1,356 has to travel tocontact the shell 1,360 can be calculated. Depending on the size of theshell, release can continue with temperature cycling until the shell isemptied. In an alternative embodiment to the one illustrated in FIG.108, the element 1,356 may carry the shell until it encounters an objectthat prevents further travel. At this point, the thermally powereddevice attempts to advance and, in the process, pressurizes the shelland creates a path to release the substance on the surface of thecontacted object. Release of a substance upon contact can be used incases when there is a need to release a drug or chemical to the surfaceof an object to dissolve it in order to clear the pathway and the like.

The thermally powered device can be used without tracks to travel incertain mediums that will sustain it and prevent it from slidingbackwards. Such mediums include certain types of living mammalianmatter, viscous substances and particulate media. As an example, when athermally powered device travels in particulate media, the work enablersdisplace the particles of the media ahead of them as they advanceforward. These particles flow to the space left behind by the workenablers to occupy it. Once this space is occupied, they providetraction for further advancement. The same principle applies to viscoussubstances. In a living mammalian matter or other elastic substance,with each advancement of the thermally powered device the substanceneeds time to relax and flow back to re-occupy the space left behind bythe work enables before traction is available for further advancement.FIG. 103 illustrates an independent shape memory material activatedtransport device 1,290 that is similar to the previous ones with theexception that it travels without guiding tracks and it is equipped witha pointed nose 1,294 to allow it to minimize the drag resistance. FIG.109 shows an alternative embodiment of an independent shape memorymaterial activated transport device 1,400 comprising a tubulartelescoping body 1,402 configured with variable length fins 1,404 and arounded nose 1,406. The device 1,400 utilizes a telescoping body insteadof a bellows type variable length body. In both concepts, the number offins, their spacing, size, orientation and geometry must be optimizedfor the medium in which the device will travel. Preferably, the outsidesurfaces of the fins should be configured to minimize the frictionaleffects and drag during advancement and the inside or underside surfacesshould be configured to maximize the frictional resistance and thrust.Both of these objectives are achieved through modifications in surfacecharacteristics such as surface finish and the application of surfacecoatings. In addition, material properties and construction of the finsto produce selective flexibility will minimize drag and increase thrust.

FIG. 110 shows an independent shape memory material activated transportdevice 1,450 comprising a shape memory material body 1,452 that performsas a variable length body as well, and a bias spring 1,454 that forcesit to return to martensitic shape upon cooling. The fins are integralwith the body. The device 1,450 provides opportunities for applicationsrequiring small advancements with temperature cycling and a minimumcross sectional area. FIG. 111 shows an independent shape memorymaterial activated transport device 1,500 comprising a multi-part body1,502 and a shape memory material spring trained in two way shape memoryeffect 1,404. The device 1,500 provides for flexibility in following anon-linear trajectory. This concept can be equipped with tracks as wellto go around tight curves. Also, a bias spring may be added. To follow acurved course of a constant curvature, the variable length body of anythermally powered device can be made curved such that the curvature doesnot change with expansion and contraction.

An independent shape memory material activated transport device oncedeployed can be retrieved using a set of tracks. By placing the tracksin front of the device as it travels, it will be forced to enter thetrack. By withdrawing the track, the device is retrieved. In this case,the track act as a catcher.

Fins for the thermally powered devices do not have to be fixed. They canbe hinged to provide limited movement such as to minimize the dragresistance and increase the thrust. In addition, they can be made ofmultiple parts to allow for greater flexibility and travel on variablewidth or diameter tracks. Also, they can be reversible to allow fortravel in both directions. FIG. 112 illustrates a reversible fin-shapememory material activated transport device 1,550 comprising a thermallypowered device 1,552 with inwardly extended fins 1,554, a closed endtrack with a rough surface 1,556 and a shuttle bracket 1,558. Theshuttle bracket 1,558 is configured with openings through which the finsare inserted. The inwardly extended fins 1,554 are hinged at the edgesof the thermally powered device 1,552. The device 1,550 advances withtemperature cycling, with the rough surface of the track provingtraction, until the shuttle bracket 1,558 encounters the end of thetrack. At this point, the device attempts to overcome the resistanceoffered by the bracket and in the process the bracket forces theinwardly extended fins 1,552 to reverse direction by rotating about thehinge and allow the device to begin traveling in the opposite direction.The rotation is afforded by the flexibility of the fins that have tobend in order to allow the rotation to take place. When the devicereaches the other end, the fins are forced to rotate to their initialposition and travel begins in the initial direction. Rotation of thefins can also be achieved with different engagement-disengagementmechanisms that may incorporate clutches, cams, springs, ratchet gears,multi-link fins and the like. Reversible thermally powered devicesprovide an extended life for multiple release applications. In addition,release can take place at both ends of the track at a predeterminedperiod of temperature cycles. By configuring this device with twoelements one at each side, instead of single element 1,356 asillustrated in FIG. 108, its capability increases considerably since itcan perform similar or different tasks at each end repeatedly as itshuttles back and forth. Reversibility of the thermally powered devicescan be extended to devices containing non-fin type work enablers byincorporating mechanisms that are either available commercially or whoseoperation principles are well established. As an example, the wheelsused as work enablers in FIGS. 98 to 100 can become reversible with theincorporation of reversing ratchets. These ratchets use a double enddetent and by simply changing its position the wheel rotation can changedirection. Actuation to change the position of the detent can beachieved by simple mechanical means with the detent connected to ashuttle type mechanical member via a linkage system. When the mechanicalmember is pushed against an obstacle or pulled externally, the detentsof the wheels reverse their rotation and the thermally powered devicebegins advancing in the opposite direction.

Thermally powered devices, whether traveling on an open, closed or looptrack, are capable of becoming temperature indicators and warningsystems by releasing a substance. They can achieve the same functionthrough their relative position on the tracks without having to releaseany substance. This position can be determined through direct visualobservation of the device adjacent to a graduated scale. Preferably, thetemperature record would be observed easier with a pointer attached tothe thermally powered device pointing its exact position on thegraduated scale.

The shape memory material activated transport devices can also be usedto expand a closed conduit laterally such as a tubular passage or toincrease the gap defined by the spacing of two surfaces. In addition,they can release a substance such as a drug or sealant to provide acurative agent or to seal the wall. Further, they can expand and place aretainer such as a stent or other support member to hold the conduit inthe expanded position, to provide structural support or to form a sealedjoint. Furthermore, they can transport diagnostic and detectionequipment such as optical or acoustic devices for the inspection ofpipes or the examination of cavities in mammalian bodies such as thecolon. Samples of these devices are shown in FIGS. 113 to 119. FIG. 113illustrates a tubular expansion device 1,600 comprising a shape memorymaterial activated transport device having a collapsible tubular track1,604, configured with fins 1,608, inside of which the thermally powereddevice 1,602 configured with a nose 1,606 that aids the travel process.The purpose of this device is to expand another tube or lumen 1,610 to alarger diameter. FIG. 114 shows a circumferential cross sectional viewof the track in the collapsed position at a location A-A indicated inFIG. 113. The tubular track 1,604 collapses between the fins 1,608 toform axial folds and to assume a smaller diameter. The diameter of thecollapsed track is smaller than the diameter of the unexpanded portionof the tube 1,610. The difference in diameters allows the insertion ofthe tubular track 1,604, in the collapsed condition, into the unexpandedportion of the tube 1,610. As the thermally powered device 1,602advances forward the collapsed tubular track 1,604 unfolds with the aidof the nose and the larger diameter of the thermally powered device andforces the tube 1,610 to expand. Expansion takes place only during onehalf of the temperature cycle with the advancement of the forward end.When the aft end advances, the forward end remains stationary. The trackmay remain in the expanded position or may revert back to the foldedposition once the thermally powered device goes by. An alternativeconcept to the folded track is to use a set of individual single tracksin a cluster form that opens up as the thermally powered device advancesforward.

FIG. 115 shows a device 1,650 that is similar to the one shown in FIG.113, except that the thermally powered device travels on a monorailtrack 1,656 and the variable length body consists of two telescopinghalves, an outer one 1,652 and an inner one 1,654, forming a hollowcylindrical body that is able to expand and contract axially. The workenablers in the form of fins, or other configurations, are placed on theinside (hollow) surface. In order to allow expansion and contraction,there are no work enablers on the overlapping section of the outer half1,652 of the variable length body. Typically, the monorail track 1,656has a much smaller profile than the collapsed tubular track 1,604 ofFIG. 113 and can be inserted in smaller diameter tubes 1,658 to guidethe thermally powered device and to expand them.

The variable length body of any thermally powered device can becomecollapsible such that it expands while it travels with one temperaturecycle and collapses while it travels with the second half. This allowsfor the selective or continuous expansion of passages. FIG. 116illustrates a collapsible tubular expansion device 1,700 that is similarto the one illustrated in FIG. 115. In the present case, the twotelescoping halves of the thermally powered device 1,702 are made of anelastically deformable material that has one shape in the free state andanother one in the stressed state. FIG. 116 represents the free state ofthe variable length body while FIG. 116A represents the stressed state.In FIG. 116 the shape memory material spring is in the martensitic statewhile in FIG. 116A it is in the recovered austenitic shape. In FIG. 116Athe aft end of the thermally powered device has advanced forward and itslength has been shrunk. The forced axial shrinking of the thermallypowered device applies a stress to the outside sections of the variablelength body, causes a barreling effect, and forces it to increase itsdiameter. In turn, the increase in the diameter causes the tube 1,704 toexpand. During the second half of the temperature cycle, when the shapememory material spring undergoes reverse recovery, the variable lengthbody stretches forward, goes back to its free state and its diameterdecreases to its original size. With the repeated contraction-expansionof the thermally powered device the tube 1,704 expands incrementallywith expanded tube portions overlapping from cycle to cycle.

The same principle used to expand a tube diametrically can also be usedto shrink a tube diametrically. For this to take place, the thermallypowered device must have the work enablers on the outside and travelinside a track. In addition, it must have sufficient core clearancealong its length for the tube, that is to be shrunk, to run through it.The tube is shrunk in a reverse manner to the one shown in FIG. 116A.The inner surface of the thermally powered device expands inwards, uponheating or cooling of the shape memory material, compresses the tube andshrinks it by a predetermined amount. The expandable type devices, canbe axially segmented to allow for in-situ assembly. This requires thatshape memory material springs, with the identical hysteresis curves andcoupled with compatible bias springs, are incorporated in the differentsegments.

The variable length body made of an elastically deformable material canbe utilized as a bias spring, thereby eliminating one element from thedevice. In addition, the variable length body can be made of a number oflongitudinal leaf springs that collectively act as a bias spring.Further, a linkage can be incorporated to produce the lateral expansion.FIG. 117 shows an example of a lateral expansion device 1,750, where twoidentical links 1,752, each connected to one of the two halves of thevariable length body, are both connected to another link 1,754 at acommon point. The included angle between the two identical links 1,752changes as the variable length body expands and contracts. Duringcontraction, the included angle decreases and forces the third link1,754 to move radially away from the axis of the thermally powereddevice and apply a stress to tube 1,756 and expand it. There are severaltypes of linkage systems that can be used in conjunction with thetubular expansion device. However, the discipline of kinematics is welldeveloped and this device can adopt any suitable linkage system.

The lateral expansion device can also release a substance during thetube expansion process. All substance release concepts presented hereincan be used for this purpose. An additional concept of a lateralexpansion device is shown in FIG. 118 where a device 1,800, that issimilar to the one illustrated in FIG. 117, incorporates a shell 1,802containing a substance on the outer layer of the variable length body.As the variable length body contracts axially during the circumferentialexpansion process, the shell shrinks, the substance contained in it ispressurized, the shell wall is converted into a permeable one and thesubstance is released through it. One of the advantages of this conceptis the direct release of the substance to the tube surface upon contact.In addition, a shell of sufficient stiffness can be detached, in theexpanded shape, from the thermally powered device upon shrinking and beleft in place upon withdrawal of the device. The detached shell is leftin the expanded position in contact with the wall of the conduit (tube,lumen or vessel) and with a path created to release its substance. Thedetached shell can perform multiple functions of releasing a substance,providing structural support to the conduit or sealing a leak at thewall. Prior to its expansion and subsequent detachment, the shell can beheld on the surface of the thermally powered device by methods suchdimensional interference or a low tack adhesives. The substance to bereleased on the contact surface may be contained in a shell or anexpandable matrix that constitutes the shell or be held on the surfaceof the thermally powered device if it is in the solid form orsubstantially viscous. However, the substance released upon contact withthe tube wall can be of any state of matter and its release rate can becontrolled with similar means (permeable membranes, pressurants etc.)described herein. The substance may be dissolved or react with itssurroundings upon release or stay inert. Typically dissolution orreaction is required for biological and chemical operations andinertness for mechanical operations where the released substance mightbe a sealant or an adhesive used to bond on internal ring to a tube. Oneadvantage of the inner track is that while the device is in the expandedposition, it can be pulled out and leave the device in place. This ispossible due to the favorable orientation of the work enablers and thetendency of the expanded device to stay in place due to the hoopstresses that exist at the outside.

Besides expanding a tubular conduit and releasing a substance, anycollapsible tubular expansion device can be used to expand an objectsuch as a tube segment, ring, stent or a specific device and place it inits expanded form on the inner wall of a conduit such as a tube or ablood vessel. The purpose for the placement of such objects includes; toprovide structural support, maintain the specific shape, seal a surface,monitor a the performance of a system and the like. This is achieved byproducing an interference, snug, fit between the object to be expandedand the variable length body prior to inserting them in the tubularconduit or simply bonding the two together with low tack adhesive. Thecollapsible tubular expansion device along with its load, the object,are inserted inside the tubular conduit and at the proper location thetemperature of the shape memory material spring is raised and itundergoes shape recovery. The shape recovery causes the variable lengthbody to expand laterally and forces one of its ends to advance.Expansion of the variable length body forces the object to expandagainst the wall of the conduit and stay in place after the collapse ofthe variable length body. In addition to round objects, other non-roundobjects or partially round such as patches can also be placed providedthey have the ability to stay in place by mechanical, adhesion or othermeans. Further, the expanded objects may be combined with a shell toperform the additional function of releasing a substance.

The shape memory material activator of the thermally powered device canbe heated and cooled by changes in ambient temperature. In addition, itcan be actively heated by direct contact, forced heating or resistanceheating by an electric source, either induced or direct. In the case ofthe electric source, the shape memory material becomes part of theelectric circuit and its relatively high electrical resistance producesthe required heat to raise its temperature through the transformationrange. The thermally powered device can travel and expand laterally inthe same fashion as described herein without the utilization of a shapememory material. This requires the powering of the device withalternative means such as fluid pressure mechanical or electricalenergy. The fluid pressure can be either hydraulic or pneumatic. Byrunning supply lines to the device, the device expands and contactsfollowing the pressurization-depressurization cycle, as in the case ofthe thermal cycle, and in the process advances forward similarly to thedevice that is configured with a shape memory material activator.Typically, for most applications, fluid pressurization, pneumatic orhydraulic, requires the sealing of the thermally powered device or apressure chamber within the device to avoid leaks. Utilization of fluidpressure does not alleviate the need for a bias spring. The bias springis required to aid the contraction process and to advance the aft end ofthe device. In addition to fluid pressure, the device can be operated bya cable release system that applies a force at one end of the device toexpand it or contract it and, upon removal of the force, the process isreversed by the bias spring. Again, the device is able to travel withthe repeated application and withdrawal of the force. One advantage ofthe cable release system is that it can be attached either to theinternal or external surface of the device, at either the forward or aftend. Attachment to either end allows for the applied force to be eithertensile or compressive and to either expand or contract the device. Whenthere is no need to expand the device laterally, application of fluidpressure is restricted to devices whose variable length body can expandonly axially with internal pressure. Examples of this are bellows andrigid telescoping tubes. The thermally powered device is also capable oftraveling by the utilization of electrical energy to operate deviceslike motors or electromagnets. With these devices, the bias spring isneeded only if the variable length body is actuated in one directiononly.

The variable length body in all tubular expansion devices can be madeeccentric such as to expand tubes laterally to non-circular crosssections. This is achieved by placing the variable length body's axis ata distance from the track's axis or by making the variable length bodynon-symmetrical. The two axes may or may not be parallel to each other.FIG. 119 illustrates an alternative example of an eccentric tubularexpansion device 1,850 that is similar to the shape memory materialactivated circular transport device, illustrated in FIG. 96. In thiscase, the thermally powered device 1,854 travels on the inside track1,852 only and the outside track is replaced with an outside housing1,856. The outside housing 1,856 can be attached to the thermallypowered device 1,854 to rotate with it or it can be made of anon-rotating flexible material that accommodates the thermally powereddevice 1,854 by stretching as it advances around the track. This devicecan also be used as a cam. When used as a cam, it becomes aself-generating motion device that, unlike mechanical cams that convertregular rotary motion to irregular rotary or reciprocating motion,converts thermal energy to irregular rotary or reciprocating motion. Inaddition to the asymmetric or the eccentric housing, eccentric motioncan also be produced by utilizing a non-circular inner track.

Rotating devices, circular or eccentric, when equipped with abrasivemeans on their outside surfaces can be used to grind a shell's substanceand release it by abrasion. Further, they can grind the inside wall of aconduit to abrade away any deposits such as corrosion products in a pipeor plaque in an blood vessel. In certain cases, depending on the natureof the deposits and the flexibility of the tube, the simple lateralexpansion of the thermally powered device can be sufficient to breakloose the deposits. By incorporating an adhesive layer on the outsidesurface of the thermally powered device, loose deposits will adhere toit and be carried away upon withdrawal of the device.

Thermally Driven Track

FIGS. 120 to 144 relate to devices that are similar to the shape memorymaterial activated transport device illustrated in FIGS. 90 to 108, withthe exception that the thermally powered device is not free to travelbut it is anchored at one point along its body while the tract remainsfree to travel. With this concept, the thermally powered device becomesa self-powered device and acts as an engine to drive the track. FIGS.120 to 122 illustrate a thermally driven track device 2,000 comprising athermally powered device 2,004 mounted on an unrestrained track 2,002.This device is similar to the shape memory material activated transportdevice 1,020 illustrated in FIG. 90. In this case, the thermally powereddevice 2,004 is anchored at the forward end such that this end isrestricted from expanding and the track is free to move. FIG. 120illustrates the device 2,000 in its initial position with the shapememory material spring in the martensitic state. FIG. 121 illustratesthe device 2,000 after shape recovery. During this process, the shaperecovery force reacts against the anchored end and forces the thermallypowered device 2,004 to expand in the reverse direction. Reverseexpansion is possible only with the movement of the unrestrained track2,002 due to interlocking of the fins. The track is forced to move adistance “x” which is equal to the expansion of the thermally powereddevice. Since one end of the thermally powered device remains fixed, itsexpansion is not uniform. The relative expansion along the length of thedevice is proportional to the distance from the fixed end. At this endexpansion is 0% and at the other end it is 100%, which in absolute termsis equal to distance “x”. Due to the proportional expansion, the finsalong the length of the thermally powered device move by proportionalamounts. On the other hand, all the track fins move by the same distance“x”. To account for the proportionally unequal movement between the twosets of fins, one of the two sets or both must be flexible toaccommodate one fin to move past the other by bending elastically. As aminimum only one set of fins at the free end of the device is requiredfor functionality. FIG. 122 illustrates the device 2,000 in its finalposition after reverse shape recovery. During this process, the biasspring contracts and forces the thermally powered device 2,004 tocontract by moving the aft end forward and returning it to its initialsize. There is no movement of the track during this second half of thetemperature cycle as the fins do not lock. They accommodate each otherby bending elastically and slide past each other with minimal frictionwithout engaging each other. In cases where work enablers other thanfins are employed, whether they are wheels, gear teeth, surface effectssuch as grooves, rough surface finish, and the like, the frictionaleffects in the direction of contraction are minimal and allow thethermally powered device to contract freely.

This concept forms the basis for a multitude of applications. Using thesame concept as illustrated in FIGS. 120 to 122, but anchoring thethermally powered device 2,004 at the aft end, the unrestrained tracktravels the same distance. However, the track travels only during thesecond half of the temperature cycle when the shape memory materialspring undergoes reverse shape recovery process. The anchoring pointdetermines the portion of fins that would engage the track fins at eachhalf of the temperature cycle. If the thermally powered device isanchored at mid-body, the track will travel equal distances during bothhalves of the temperature cycle. FIGS. 123 to 125 illustrate a thermallydriven track device 2,050 with a thermally powered device 2,054 anchoredat mid-body. In FIG. 123 the thermally powered device 2,054 is at itsinitial position with the shape memory material spring in themartensitic state. FIG. 124 illustrates the device 2,050 after shaperecovery. During this process, the shape recovery force reacts againstthe anchored end and forces the thermally powered device 2,054 to expandin both directions. During this half of the temperature cycle, theunrestrained track travels one-half the distance “x/2” of the distancetraveled when the thermally powered device was anchored at one end. Thisis due to the fact that during the expansion process only half of itsfins engage the track's fins and apply a force to move it. FIG. 125illustrates the device 2,050 in its final position after reverse shaperecovery. During this process, the thermally powered device 2,054contracts by moving both ends toward the anchor point and returns to itsinitial size. During contraction, the track travels a distance equal tothe one traveled during expansion “x/2” and in the same direction. Thefins that did not participate in the advancement of the track during thefirst half of the temperature cycle are the ones that lock with the finsof the track and advance it this time. The distance traveled with eachhalf of the temperature cycle is proportional to the distance of anchorpoint from thermally powered device ends. For devices with sameorientation fins, the determining factor as to which one will contribute0% and which 100% is based on whether the shape memory material willexpand or contract during the shape recovery process. By anchoring thethermally powered device at different points along its length, therelative distances traveled in each half cycle can be set.

Multiple thermally powered devices can be utilized on the same track toproduce additional travel or higher overall recovery forces. FIGS. 126and 127 illustrate the martensitic and austenitic states, respectively,of a thermally driven track device 2,100 with two thermally powereddevices 2,102 mounted on the same track and anchored at their forwardends. They are of the same size, both expand during shape recovery, andboth have identical hysteresis curves. During the heating portion of thetemperature cycle, both devices expand simultaneously by a distance “x”.Because of the simultaneous expansion, the net distance traveled by thetrack is also “x”. Had only one thermally powered device be employed,the total distance traveled by the track would be the same. However, hadthe track been constrained from traveling, the resultant constrainedforce would have been twice as large. If on the other hand, eachthermally powered device is activated at a different temperature andthere is no overlapping of the hysteresis curves, the total distancetraveled would be twice as long. If the track is constrained fromtraveling, an initial constraining force will be developed, as thedevice with the lowest A_(s) temperature is activated first will stopincreasing in value once the A_(f) temperature is reached. If thetemperature increases further, the second device will be activated andbegin to develop a constraining force. Again, this force will stopincreasing once the A_(f) temperature is reached. By adding multiplethermally powered devices to a track several objectives can beaccomplished by the proper selection of shape memory material propertiesand track sizes. In one case, track travel can be extended withincreasing temperature if the devices are activated sequentially withrising temperature. In another case, a high constraining force can bedeveloped if the devices are activated in simultaneously with risingtemperature. In other cases, by mixing and matching transformationtemperatures, different profiles of displacement and constraining forcescan be produced with rising and falling temperatures of the shape memorymaterial activators.

By placing several thermally powered devices of different lengths andhysteresis curves anchored at different points along their lengths onthe same track, various profiles of track travel with respect totemperature can be achieved. Such profiles include, but are not limitedto: (a) Continuous travel if the A_(f) temperature of one device is thesame as the A_(s) temperature of another device. (b) Discontinuoustravel when the A_(s) temperatures of one device is higher that theA_(f) temperature of another device. (c) Continuous or discontinuoustravel during heating and cooling of the shape memory materialactivators by anchoring the devices at different points along theirlengths. In each case, the travel rate with respect to temperature canbe varied by selecting shape memory material of different hysteresisslopes. In addition to employing thermally powered devices that expandwith the rise in temperature, similar effects can be achieved withthermally powered devices that contract during the rise in temperature.

In addition to the design flexibility offered by choice oftransformation temperatures and anchoring points, selection of trackswith opposing, non converging, fins offers one more degree of freedom.FIG. 128 illustrates a thermally driven track device 2,150 comprising adiverging fin thermally powered device 2,152 with a row of forwardlyextending 2,156 and a row of backwardly extending 2,154 fins and, a setof track rails with opposing, non-converging, forwardly extending 2,158and backwardly extending 2,160 fins. The fin direction of the track isdetermined in relation to the fin direction of thermally powered device2,152. The tracks can move in opposite directions with temperaturecycling. FIG. 128 shows the diverging fin thermally powered device 2,152anchored at one end with the shape memory material spring compressed inthe martensitic state. FIG. 129 shows the same device 2,152 in theexpanded position after shape recovery. During the expansion process thefins 2,156 of the diverging fin-thermally powered device 2,152 and thefins of the track 2,160 engage and force the track to advance a distance“x” in the direction of expansion. FIG. 130 shows the diverging finthermally powered device 2,152 in the contracted position after reverseshape recovery. During the contraction process the fins 2,154 of thediverging fin thermally powered device 2,152 and the fins of the trackrail 2,158 engage and force the track rail to advance a distance “x” inthe direction opposite to the expansion direction. The advantage of thissystem is that tracks integrated with a single diverging fin thermallypowered device can travel in opposite directions with each temperaturecycle. When the tracks are restrained from traveling, constrainingforces of opposite directions are developed. Again, as with otherconcepts presented herein, instead of fins other work enables such aswheels, or gear teeth can be utilized.

The thermally driven track does not necessarily have to be straight. Itcan be of any configuration that will advance with the application ofshape recovery force. FIG. 131 shows a circular thermally driven trackdevice 2,200 comprising a circular outer track 2,210 configured with aplurality of inward fins 2,212, a circular inner track 2,214 configuredwith a plurality of outward fins 2,216 and a circular thermally powereddevice 2,220 anchored at mid-body along its circumference. The circularthermally driven track device 2,200 is similar to the one illustrated inFIG. 96 with the circular thermally powered device 2,220 anchored atmid-body and the outer 2,210 and inner 2,214 tracks free to rotate. Thecircular thermally powered device 2,220 comprises a curved variablelength body 2,206 with a plurality of fins 2,208 and houses a shapememory material spring 2,202, and a bias spring 2,204. The fins 2,208 ofthe variable length body 2,206 and those of the outer 2,212 and inner2,214 tracks are skewed to lock the tracks in one direction and to allowthem to rotate freely in the opposite direction by flexing and slidingpast each other. With the circular thermally powered device anchored atmid-body, both the inner and outer tracks rotate during the heating andcooling cycle of the shape memory material spring by the same angle. Oneof the advantages of the circular thermally driven track devices istheir ability to convert linear motion to rotary motion and to developtorque when the motion is restrained. They perform this function whilethe temperature changes within a predetermined temperature range.

The angular degree of rotation in each half cycle is half of the angularexpansion of the circular thermally powered device. As was the case withthe straight track, by anchoring the circular thermally powered deviceat different points along its body, the relative amounts of trackrotation between heating and cooling can be adjusted. All thermallydriven track systems presented herein can operate, as a minimum, with asingle traveling track provided there is sufficient support to eliminatedistortion of the thermally powered device and to keep it on track. Asan example, the circular thermally powered device 2,200 can operatewithout the inner track fins 2,216 provided the inner track providesguiding support to the circular thermally powered device 2,200. Ofcourse, with a monorail system as the one shown in FIG. 95, there is noneed for a second track.

Production of rotary motion is not limited to concentric tracks only.Other embodiments utilizing such means as gears, shafts, belts, orchains can be utilized. FIG. 132 illustrates the gear system 2,250comprising a thermally powered device 2,252 with gear teeth 2,254 aswork enablers, coupled with two gears 2,256. The thermally powereddevice 2,252 is anchored at one end and, as it expands and contacts withtemperature cycling, it drives the gears 2,256 back and forth. In thiscase, the gear teeth geometry does not allow for bending and sliding, aswas the case with fins, and the gears have to rotate back and forth. Thethermally powered device can be coupled with other circular tracksystems to produce rotary motion. Instead of building a circularthermally driven system in a planar form, as is the case with theembodiments illustrated in FIGS. 131 and 132, the tracks and thethermally powered device can be integrated in a three dimensional mannerfor compactness and enhanced capabilities. For example, by powering twoparallel circular tracks of equal size by a thermally powered deviceplaced between them, the power will be distributed equally between thetwo. However, this is not the case with the planar arrangement of theconcentric tracks (outer and inner tracks) shown in FIG. 131.

The thermally powered device's body does not have to be flexible in theform of a bellows, neither does it have to be made of one single part.It can be made of tubular telescoping parts requiring a minimum of onlyone set of fins at the aft end if the thermally powered device isanchored at the other end, or two sets (one at each end) if it isanchored elsewhere along the length of the body. Also, the thermallypowered device's body can be an elastomer that performs as a bias springand can encapsulate the shape memory material spring and become anintegral part with it. In this case, the fins can be extensions that aremolded or sculptured on the body. Further, the thermally powered devicecan have no body if the fins are attached to the shape memory materialspring directly. The fin spacing on both the track and the bodydetermine the precision of motion transferred from the thermally powereddevice to the tracks. Typically, the finer the spacing, the better themeshing between the two sets. Again, the shape memory material spring aswell as the bias springs can have any configuration. They do not have tobe coil springs. As long as the shape memory material can be deformed atone temperature and recover its shape at another temperature byproducing a displacement when left unrestrained and a force when it isrestrained, it will perform adequately in the devices presented herein.Also, for all the devices presented herein, functionality is independentof shape and size of shape memory material and bias springs. Further,functionality is independent of fabrication and assembly methodsutilized to build the devices. The bias spring must have the ability tobe deformed elastically by the shape memory material spring during theshape recovery process and produce, as a minimum, a force sufficient toaid the shape memory material spring in its reverse shape recoveryprocess and return it to its deformed cold shape. For metallic shapememory materials such as the nickel-titanium based alloys, themartensitic condition is the cold shape.

The energy generated by thermally powered devices can be utilized tocreate a path in a shell to release a substance. A linear or rotarythermally driven track device can be used for this purpose. Linear orrotary motion can be used to create a path in shell wall to release asubstance by fracturing, exploding, imploding, puncturing, peeling,tearing, shearing, grinding, rupturing, splitting, twisting, stretching,squeezing, separating, debonding, grinding and the like, a shell. Thepath creation can take place with rising and/or falling of the shapememory activator's temperature. In addition, by adding several thermallypowered devices to the same track system, a reversible type path can becreated repeatedly over different temperature segments. The energygenerated by thermally powered devices can be used for other purposesbesides path creation. At times, it becomes beneficial if it istransferred to other devices by mechanical means. FIG. 133 Illustratesan example of a thermally driven power transmission device 2,300comprising a circular thermally driven track device 2,302, and a wheel2,306 connected to it with a belt 2,304. As the thermally driven track2,302 rotates with changing temperature, the belt 2,304 transfers themotion to the wheel 2,306. The wheel 2,306 to which the circularthermally driven track device 2,302 is coupled can be of any size suchas to either increase or decrease the angular rotation or the resultingtorque. Besides the outer track, the inner track can also be used totransfer energy to another wheel. Instead of a belt, other flexiblepower transmission means such as chains, gears or shafts can be used totransfer motion. In both cases, several thermally powered devices can beincorporated on a single thermally driven track to produce motion overan extended temperature range, increase the torque, and produce motionin two directions during with the rise or fall of temperature.

Instead of a free rotating wheel, two or more circular thermally driventrack devices can be coupled together with a belt to produce deviceswith enhanced characteristics. Such a device 2,350 is shown in FIG. 134where the fins of the outer and inner tracks of both thermally driventrack devices 2,352 and 2,356 are oriented the same direction. Each ofthe thermally driven track devices 2,352 and 2,356 incorporates a singlethermally powered device 2,354 and 2,358, respectively. Orientation ofthe fins in the same direction assures rotation of both devices 2,352and 2,356 in the same direction. The thermally powered devices 2,354 and2,358 are anchored at opposite ends such that if the shape memorymaterial springs have identical hysteresis curves and both expand by thesame amount during shape recovery, the thermally driven track device2,352 will rotate clockwise during the shape recovery processes and thethermally driven track device 2,356 will rotate clockwise during thereverse shape recovery process following the path of the hysteresiscurve. This way, the belt connecting the two devices will be advancingin the same direction by the same amount in both times. If thehysteresis curves are nested inside each other, overlap or are spacedapart, rotation will take place in the same manner. However, thetemperature span between the two sequential advancements of the beltwill change. In addition, if ambient heating is used, the temperaturecycle must encompass the hysteresis curve width of both shape memorymaterial springs and any span between them to assure complete recoveryof both springs and return to martensitic state. If each shape memorymaterial spring is heated individually such as by electric heating,their respective temperature cycles will based on their individualhysteresis curves. If the thermally powered devices illustrated in FIG.134 are anchored at the same ends, both will rotate simultaneously withthe rise in temperature if the hysteresis curves are identical orsequentially if they are different. If the hysteresis curves overlap,part of their shape recoveries may coincide and during this temperaturesegment, both devices will be rotate. Simultaneous rotation increasesthe torque of the system but not increase the advancement of the belt.

In the case where the fins of two coupled thermally driven track devicesare oriented in opposite directions, the thermally powered devices willalso rotate in opposite directions. Unless both shape memory materialsprings have similar or overlapping hysteresis curves, the thermallypowered devices will not counter rotate simultaneously. By rotating atdifferent temperatures, a back and forth rotation is generated. Byselecting the shape recovery characteristics of each shape memorymaterial spring, the temperature span between rotations and will be set.If there is simultaneous counter rotation, there will be no net rotationdue to restrained motion, resulting in tensile stress in one span of thebelt (or connecting member) and compressive stress on the other.Different combinations of fin orientation, anchoring points and shapememory material properties can be used to produce repeated motion withrising or falling temperatures within predefined temperature ranges. Theresulting motion can be (a) unidirectional, where a set or tracks or abelt move in one direction, (b) bi-directional, where two tracks of thesame track set move in opposite directions, or (c) oscillating, where aset of tracks or a belt go back a forth between two or more positionswithout making an overall net advancement. In all cases, when the motionis restrained, a force develops that can be converted into torque withrotary systems. These concepts can be used in applications such as; tocreate a path to release a substance, to accumulate torque, to apply acontrolled force at given location, or generally to actuate or to powerother devices.

When the shape memory material activators are actively heated,incorporation of multiple devices into one system enhances the system'soutput considerably. If heating is sequenced to allow one activator tocool to the martensitic state while another is heated to austeniticstate such that at any time there is at least one activator powering thesystem, continuous rotation will be produced.

The concepts of thermally powered devices and thermally driven trackdevices can be used to create paths through shells to releasesubstances. In addition, they enhance the path creation process in termsof release types, temperatures, repeated cycles, delayed cycles and thelike. FIG. 135 shows an extrusion type release device 2,370, comprisinga linear thermally driven track device 2,376, a shell 2,372 in the formof a syringe and a piston 2,374 connecting the two. As the thermallypowered device expands during heating, the track applies pressure to thepiston 2,374 that in turn transmits it to the substance contained in theshell 2,372 and creates the path to release it. Release takes place byextruding the substance through a nozzle, needle, valve or other openingthat may contain a permeable membrane, filter, etc. With this concept,the substance is released only during the heating of the shape memorymaterial spring. Once the A_(f) temperature is reached, the releasestops as there is no longer a force applied by the track. Path creationcan also take place during cooling from the M_(s) temperature simply byanchoring the thermally powered device 2,370 at the other (front) end.Anchoring between the two ends will take place both with rising andfalling temperatures. However, the amount of substance released duringthe rising of the temperature will be a multiple of the fraction definedby the relative distance of the anchor point from the end to the totallength of the thermally powered device. For a thermally powered devicethat expands and contracts linearly, the amount of substance releasedper degree of temperature change remains constant.

FIG. 136 shows a shape memory material based release device 2,380 thatoperates in a rolling fashion, but releases the substance similarly tothe extrusion process concept. In this case, a circular thermally driventrack device 2,384 is utilized and the path is created by a rollingprocess. The circular thermally driven track device 2,384 rotates as thetemperature rises above A_(s) and the shell 2,382 passes under it. Theshell, as it becomes deformed by the rolling process, is forced todecrease volume, increase the internal pressure and to create a path torelease the substance. In this process, a path is created bypressurizing the substance in a similar fashion as in the previousconcept, FIG. 135. In the present example, the thermally driven trackdevice 2,384 is anchored at its mid-body and as such it rotates andcreates paths both during heating and cooling.

FIG. 137 shows an example of a grinding release device 2,390. Thethermally driven track device 2,394 applies an external compressiveforce to a shell 2,392 and as it rotates, during heating and cooling inthis case, it grinds against the shell 2,392 that consists of asubstance that is releasable by abrasion. The outer surface of the wheelmay have a rough surface finish or may contain adhered abrasionparticles to aid the grinding process.

FIG. 138 illustrates a shape memory material activated unrolling releasedevice 2,400 that creates a series of paths by a peeling process. Thisdevice 2,400 comprises a circular thermally driven track device 2,408that is utilized to peel off the peelable layer 2,404 from a series ofshells 2,402 constructed sequentially on a tape spooled on a springloaded reel 2,406. The reel 2,406 is spring loaded in order to providetension during the peeling process. The expansion and contraction of thethermally powered device and the spacing of fins can be adjusted tocorrespond to the spacing and length of the shells, such that with atemperature change there is a predetermined number of shells that wouldrelease their substance. The change in length of the thermally powereddevice, along with its anchor point, determine the number of shellsreeled off and thereby the number of paths created with each half of thetemperature cycle, while the fin spacing determines the precision of thesystem. Advantages of this system include simultaneous creation ofmultiple paths in shells each containing a different substance when theyare arranged in parallel to each other on the tape, and thepredetermined number of path creations per degree of temperature changeof the shape memory material activator.

FIG. 139 shows an example of a dual squeeze release device 2,450comprising two linear thermally driven track devices 2,452 and 2,454,each containing a single thermally powered device 2,460 and 2,462,respectively, placed at either end of an accordion type shell 2,456. Thetwo thermally driven track devices 2,452 and 2,454 are employed tocreate a path through the wall of the accordion type shell 2,456 bysqueezing it. As the shape memory material springs undergo shaperecovery, the thermally powered devices 2,460 and 2,462 force theirrespective tracks to move in the direction of the shell 2,456 and applycompressive stresses on it. These stresses result in the pressurizationof the shell and the consequent release of the substance through a pathcreation process. The path can be created through increased wallpermeability, incorporation of unidirectional flow valves, and the like.The thermally powered devices 2,460 and 2,462 are anchored at theirrespective midpoints such that they advance their tracks and releaseequal amounts of substance with each half of the temperature cycle. Thepressure exerted by each thermally driven track on the shell issufficiently large to release the substance but not to deform thethermally powered device of the other thermally driven track. Further,provisions can be made to prevent the force applied by one device formtransmitting to the other. If heating and cooling of the shape memorymaterial springs is independent of each other, substance release isindependent of any relationship between hysteresis curves. On the otherhand, if heating and cooling depend on ambient conditions, therelationship of the hysteresis curves influence the sequence ofactivation of the thermally driven track devices. If the hysteresiscurves of different shape memory material springs have any portion oftheir A_(s) to A_(f) or M_(s) to M_(f) curves coincide with each other,both thermally driven track devices 2,452 and 2,454 will be squeezingthe shell 2,456 simultaneously, resulting in twice the normal pressure.The increased pressure will result in an increased release rate with ahigher overall release. By proper selection of the hysteresis curves,the sequence of substance release and the release rate can becontrolled. By reversing the fin orientation of each thermally driventrack, the shell will be pulled apart instead of being squeezed. Again,a path can be created to either release or admit a substance by thestretching the shell. Instead of an accordion type shell, other types ofshells whose path is created by squeezing or stretching can be used withthis device. Such shells include, but are not limited to, crushable andpeelable shells. Incorporating two thermally driven tracks in a deviceextend the operational temperature range and provide for repeatedreleases with both increasing and decreasing temperatures.

Multiple thermally powered devices can be integrated on a singlethermally driven track to produce motion at different temperatureranges. FIGS. 140 and 141 illustrate a circular thermally driven trackrelease device 2,500 comprising a fin diverging circular thermallydriven track 2,502 with a pair of thermally powered devices 2,504 and2,506 with both its outer and inner tracks connected to time dependentrelease device 2,508, similar to the one illustrated in FIG. 56, viaextension members 2,510 and 2,512 respectively. The thermally powereddevices 2,504 and 2,506 are anchored at adjacent ends and their fins areoriented in diverging directions to match those of the tracks. In thepresent embodiment, the hysteresis curves of the two thermally powereddevices are spaced apart with the lower one 2,506 having the lowestA_(s) temperature. As the temperature of the shape memory materialspring of the lower thermally powered device is raised, it expands, asillustrated in FIG. 141, and in the process rotates the inner trackcounterclockwise and creates a path to release the substance. The pathcreation takes place by converting the rotary motion of the inner trackto a linear one and transmitting it to the time dependent release devicevia the extension member 2,512. In turn, the extension member 2,512pulls the closing member of the time dependent release device 2,508open. During the path creation process, both extension members 2,510 and2,512 retract. There are several established methods such as gearingsystems and retractable tapes that can be used to achieve this. When thetemperature of the shape memory material spring of the upper thermallypowered device 2,504 is raised, it expands and rotates the outer trackclockwise to close the path. When the shape memory material spring ofthe upper thermally powered device 2,504 undergoes reverse shaperecovery with falling temperature, the device contracts and rotates theinner track counterclockwise to create the path. The lower thermallypowered device 2,504 contracts and rotates the outer track clockwise toclose the path when the shape memory material spring contained within itundergoes reverse shape recovery with falling temperature. To assurethat expansion and contraction of the thermally powered devices resultin equal displacements of the shell's closing member, the relativelengths of thermally powered device fins engaging the inner and outertracks is adjusted. A larger length of fins is allowed to engage theinner track that the outer. The inner track, being of smaller diameter,requires additional angular rotation to produce the same amount oflinear motion as the outer one.

The embodiment illustrated in FIGS. 140 and 141 demonstrates thecapability of the circular thermally driven track device to integratemultiple thermally powered devices to create, and to close, a path torelease a substance over multiple temperature ranges with repeatedtemperature cycles. In cases such as the present where a time dependentrelease device is utilized, the path remains open between temperatureranges. The path is created when one shape memory material springundergoes shape recovery and it is closed when another shape memorymaterial spring undergoes shape recovery. The release of a substance isonly one of the capabilities of these devices. The production of motionand a force with temperature change, either ambient or induced, overmultiple temperature ranges, can be utilized to power or actuate amultitude of devices. In addition to the device described above wherethe tracks are concentric and coplanar, equal or enhanced results can beachieved by arranging the different components in a three dimensionalmanner. Two or more thermally driven tracks can be arranged in parallelplanes and be driven by multiple thermally powered devices placedbetween them.

FIGS. 133 and 134 illustrated the production of linear, conveyor like,motion in one direction utilizing one or more thermally driven trackdevices. FIG. 142 shows an example of a counter-rotating device 2,550with two thermally driven track devices 2,554 and 2,556 connected with abelt 2,552, having a lever 2,564 attached to it, and their respectivethermally powered devices 2,560 and 2,562 anchored in opposite ends withtheir fins oriented in opposite directions. With the presentarrangement, the thermally driven track devices rotate in oppositedirections. Unless both shape memory material springs have similar oroverlapping hysteresis curves, the thermally driven track devices 2,554and 2,556 will not counter rotate simultaneously with ambient heatingand cooling. By rotating at different temperatures, a back a forthmotion is generated and the lever 2,564 oscillates within a distance “x”with each device advancing the belt 2,552 by the same amount, but inopposite direction. If there is a difference in this advancement, thelever will be moving back and forth by unequal amounts and as a result,with each device going through a full temperature cycle, it will beadvancing by a net distance equal to the advancement difference betweenthe two thermally powered devices. In cases where there is simultaneouscounter rotation, there will be no rotation as a moment would begenerated due to constrained motion that will result in tensile stressthe lower part of the belt (or connecting member) and a compressive oneon the upper. This device presents several opportunities for pathcreation and substance release applications. For example, theoscillating motion of the lever can be utilized to create a pathrepeatedly in several types of shells. Such shells include timedependent ones where part of the shell is withdrawn or slides to createa path. A sequential path can be created in several shells arranged inline, having a common sliding cover connected to the oscillating lever2,564. The cover can be configured with an opening such that when itmoves back and forth over the shells, by the action of the lever, a pathis created every time the opening lines up with a specific shell. In asimilar manner, a circular thermally driven track device can perform thesame function by rotating a sliding cover, over a group of shellsarranged in a circle.

The thermally powered device constitutes an energy conversion machine.It utilizes thermal energy and converts it into mechanical energy. It iscapable upon heating or cooling to produce motion and apply a force toperform work. When left unconstrained, it travels on a guided orunguided track. The thermally driven track device expands thecapabilities of the thermally powered device in terms of providing themeans for power transfer. When a circular thermally driven track deviceis utilized, the expansion and contraction of the thermally powereddevices is converted into rotary motion that can easily be manipulatedand transferred via mechanical power transfer mechanisms comprisinggears, belts, chains, shafts and the like. The concept of the thermallydriven track device is a modular one in that it allows for theintegration of multiple devices, interconnected with mechanical powertransfer means, to produce a system of increased work output. Themodularity of the system is not restricted by the scale of theindividual devices. This modularity provides a multitude ofopportunities for expansion in both two and three dimensions. Forexample FIG. 143 illustrates an energy conversion system in the form ofa planar thermally powered device 2,600 comprising two thermally powereddevices 2,606 and 2,608 driving a set of two identical flexible tracks2,602 with each track looping around two wheels 2,604. The fins of thethermally powered devices 2,606 and 2,608 are diverging such that theloops formed by the flexible tracks 2,602 rotate in the same direction.The thermally powered devices 2,606 and 2,608 are anchored at the sameends with the first one contracting with rising temperature and thesecond one expanding. With this arrangement, and identical hysteresiscurves, both tracks rotate simultaneously with the rise and fall of thetemperature. If the thermally powered devices are configured withcontinuous fins around their circumferences, more flexible tracks can beadded to form a three dimensional system. In addition, the wheels 2,604can be of different diameters in order to produce different values ofspeed or torque. Further, more thermally powered devices can be added toproduce rotation over wider temperature ranges. Also, continuousrotation or higher torque values can be produced by heating and cooingindividually the shape memory material springs of several thermallypowered devices. One advantage of this device is that it converts linearmotion to rotary motion. In addition, it can distribute the powergenerated by the shape memory material springs to different rotatingmembers for further usage. One such usage is the path creation torelease substances contained in multiple shells.

FIG. 144 illustrates an embodiment of an energy conversion system 2,700in the form of a three dimensional thermally powered device comprisingtwo circular thermally driven track devices 2,702 and 2,704. The firstcircular thermally driven track device 2,702 has a thermally powereddevice 2,706 mounted on its tracks and rotation from the outer track istransferred to a wheel 2,714 via a driving closed loop flexible track2,710. The second circular thermally driven track device 2,704 has athermally powered device 2,708 mounted on its tracks and rotation fromthe outer track is transferred to a wheel 2,716 via a driving closedloop flexible track 2,712. The two thermally driven track devices 2,702and 2,704 are connected via a shaft 2,722 such that rotation from theinner track of one is transferred to the other. The two wheels 2,714 and2,716 are connected via a shaft 2,724 such that rotation from bothwheels is transferred to this shaft. The two shafts 2,722 and 2,724 areconnected via a belt 2,726 such that rotation from the inner tracks ofthe thermally driven track devices 2,702 and 2,704 is transferred toshaft 2,724. The power generation is enhanced with the mounting of twotelescoping type thermally powered devices 2,718 and 2,720 on thedriving closed loop flexible tracks 2,710 and 2,712 respectively. Thepurpose of this device is to convert thermal energy into mechanicalenergy and concentrate it in a single shaft 2,724. It demonstrates thecapability of thermally driven track devices to convert energy and buildmulti-component modular energy conversion systems. The system of FIG.144 consists of four power conversion units; circular thermally driventrack devices 2,702 and 2,704 and two telescoping type thermally powereddevices 2,718 and 2,720 that utilize the driving closed loop flexibletracks 2,710 and 2,712 and belt 2,726 to transfer the generated motionto a single shaft. The work enablers, fins in this case, are orientedsuch that the direction of all rotating elements is clockwise. Allthermally powered devices 2,706, 2,708, 2,718 and 2,720 are heldstationary on one end and produce motion only during one-half of thetemperature cycle of their respective shame memory material springs. Thetelescoping thermally powered devices 2,718 and 2,720 have only one setof fins 2,728 each, mounted at the free end. More fins can be added,however, one set is the minimum required for functionality. Duringexpansion of their variable length bodies, telescoping tubes in thiscase, they force the driving closed loop flexible tracks 2,710 and 2,712to rotate clockwise. An energy conversion system such as 2,700 offersthe opportunity to add more thermally powered devices to existing tracksor modules to increase the energy conversion capacity of the system. Asa minimum, a module constitutes a thermally driven track device withmeans such as belts, chains, or gears to transfer motion to the system.

By integrating several modules comprised of thermally powered devices,tracks and connecting means, the energy conversion system can beexpanded from a linear one to a planar one to a three dimensionalsystem. Each module constitutes a subsystem that funnels the powergenerated to a single mechanical member such as rotating gear or shaft.There is no limit to the number of modules that can be combined tofunnel their power output to a common mechanical member. Thismodularization provides the flexibility of increasing the capacity ofthe energy conversion system by the simple addition of more modules. Byselecting the shape memory material springs to have different hysteresiscurves, a continuous output motion can be produced with the rise andfall of the temperature. In addition, by selecting the shape memorymaterial spring type and size along with the number of modules,different levels of energy output are achieved.

If the shape memory material springs are heated by ambient heat, energyconversion will take place during ambient temperature change. Dependingon the hysteresis curves of the individual shape memory materialsprings, energy conversion may be extended continuously orintermittently from the lowest A_(s) temperature to the highest A_(f) ofthe hysteresis curves. Also, depending on the anchoring arrangements ofthe individual thermally powered devices, additional rotation can beproduced during cooling from the highest M_(s) to the lowest M_(f)temperature. Any output during reverse shape recovery is attributed toeither the bias springs or to the two way shape memory effect.

For a higher rate of energy conversion, heating of the shape memorymaterial can be achieved by electric power. The electric resistance ofthe certain shape memory materials such as Nitinol is sufficiently highto allow them to be used as electric resistors. In this case, individualshape memory material springs are connected to a power source and heatedresistively. Heating of the shape memory material springs can besimultaneous for maximum torque production with accompanieddiscontinuous motion, or sequential such as to allow one group of shapememory material springs to cool while another group is being heated upresulting in reduced torque but a continuous rotation. Increased energyoutput requires a rapid cooling rate in order to allow for fast cycling.A large system consisting of multiple modules of thermally driven trackdevices can be used to counter the effects of slow cooling. In thiscase, at any given time, different modules or group of modules will beat different stages of heating-cooling cycle such that there is motionproduced continuously.

The shape memory material spring activators can be cooled with a movingfluid, gas or liquid, to accelerate the cooling rate. If the M_(f)temperature is above ambient, forced ambient air can be used as acooling medium. In cases where forced cooling is not possible or it isnot considered optimum, the individual shape memory material springactivators can be cooled with a cooling fluid contained in individualreservoirs. Such a self cooling device 2,800 is illustrated in FIG. 145and consists of a thermally powered device (work enablers not shown) anda cooling system. The variable length body 2,802 of the thermallypowered device is capable of containing the cooling fluid andcommunicating with two cooling reservoirs The cooling system consists oftwo flexible body reservoirs 2,808, one at each end, that communicatewith the variable lengthy body via two valves 2,810 that allow for inand out passage of the cooling fluid. The opening of two valves 2,810 iscontrolled by two links 2,812 that move apart from each other when thethermally powered device expands, opening the valves for the fluid toexit. The two links 2,812 move toward each other when the thermallypowered device contracts, reversing the direction of the valves for thefluid to enter. The movement of the links 2,812, and in turn the totaldisplacement of the valves, is controlled by a length restrainer 2,814.The total length of the device 2,800 is fixed such that when thethermally powered device expands by the shape recovery force, thereservoirs contract, and the fluid is forced to flow from the reservoirsto the variable length body.

Prior to heating of the shape memory material spring 2,804, the variablelength body is in the contracted position occupying a minimum volumewhile the two reservoirs 2,808 are in their expanded position occupyinga maximum volume. The two valves 2,810 are open toward the reservoirs asshown in FIG. 145. Due to the volume differential between the variablelength body and the reservoirs, sufficient fluid is drained into thereservoirs such the shape memory material spring 2,804 is not in contactwith the fluid. During heating of the shape memory material spring2,804, the variable length body expands as shown in FIG. 146, the tworeservoirs 2,808 contract, the two valves 2,810 reverse direction andthe fluid flows into the variable length body and begins to cool theshape memory material spring 2,804. As the cooling process progresses,the shape memory material spring undergoes reverse shape recovery andthe bias spring 2,804 forces the variable length body to contract, thereservoirs to expand, and the valves to reverse direction. With thecooling process, the fluid flows back into the reservoirs, and the shapememory material spring no longer is in contact with the fluid. As thefluid in the reservoirs is heated up with temperature cycling, the heatcan be transferred to ambient or be absorbed by another fluid in contactwith the external surface of the reservoirs. Additionally, a fluidreplenishing system can be put in place to provide a constanttemperature fluid.

FIG. 147 illustrates a similar concept as the one illustrated in FIG.145, with the exception that no valves are used. The device 2,850 ofFIG. 147 utilizes a restraining rod 2,852 with two openings 2,854, oneat each end of the variable length body, for the fluid to flow in andout of the reservoirs. The function of the restraining rod 2,852 is tokeep the overall length of the device 2,850 constant such that when thevariable length body expands, the reservoirs contract and the fluidflows into the variable length body. When the variable length bodycontracts, the reservoirs expand and the fluid flows into thereservoirs. The incorporation of two reservoirs allows the system to beorientation free. The relative sizes and shapes of the variouscomponents along with the location of the valves allow this device tooperate at different orientations, from horizontal to vertical. Asimpler version of device 2,850 is shown in FIG. 148, where a selfcooled device 2,900 utilizes only one reservoir and the need for thevalves is eliminated. In order for the fluid to flow in and wet thewhole surface of shape memory material, the device 2,900 has to operatein the vertical position. Deviations from verticality are permitted aslong as the ability to cool the shape memory material spring is notdiminished. Openings 2,904 at the bottom of the variable length body2,902 are adequate to allow the fluid to flow in and out with theexpansion and contraction process of the variable length body,respectively.

When several modules of thermally powered devices are used, individualmodules may be forced heated and cooled as groups by a circulating fluidsystem. By selecting the thermally powered devices in each module tohave the same transformation temperatures, fluid used by one module forcooling can be used in another module for heating if the M_(f)temperature of the first module is the same or higher than the A_(f)temperature of the second module. In this system, the heat oftransformation released by the shape memory material activators of onemodule during cooling is absorbed by the shape memory material springsof second one during the shape recovery process. This way, thetemperature increase of the fluid attributed to austenite to martensitetransformation in one module is reduced by the same relative amount inthe second module by the heat absorbed during the martensite toaustenite transformation. This type of closed recirculatory system tendsto minimize the energy required to operate the system.

Certain materials suffer fatigue failures when subjected to cyclicloads. In many materials, including metallic shape memory ones, fatiguelife is extended by frequent annealing treatments. To eliminate fatiguefailures in thermally activated devices, the shape memory materialsprings can be partially or fully annealed in situ prior to developingpermanent damage. Annealing removes the dislocations accumulated duringcycling and in general rehabilitates the material. When the shape memorymaterial springs are heated resistively for the operation of the device,the electric circuitry exists and can be used to anneal the springresistively, in situ. The shape memory material springs already havetheir shape and since there is no need to re-set them, no restrainingtooling is required for annealing. The annealing temperature to extendfatigue life should be kept at a level low enough not to alter the shapememory properties or the shape memory material spring. Typically, thislevel is below the temperature of the last heat treatment prior toplacing the spring in service. When bias springs are used, it ispreferable to decouple them from the shape memory material spring toeliminate the application of external stresses.

There are numerous applications for the energy conversion system. Theyrange from the specific ones such as the creation of a path to open ashell or a group of shells to release a substance, to the general use ofmechanical energy similar to the one produced by heat engines.Applications also include medical devices such as implants, or drugdelivery systems. One of the main advantages of the energy conversionsystem is the ability to be scaled up and down by either adding modulesof thermally powered devices together or by changing the size of theindividual thermally powered devices. Both options allow for an extendedrange of sizes from large scale energy conversion industrial typeapplications to MEMS (micro elecrto-mechanical systems) and nano-scaleapplications. These options are available as the function of thesedevices is independent of their fabrication method.

Arming

A problem encountered by the industry of temperature activated devicesis the requirement to keep them inactive, in a dormant state, duringmanufacturing, storage and transportation. The state of dormancy ismaintained by keeping the devices at low temperatures until thebeginning of their service life, mostly by refrigeration, in order toavoid premature activation by ambient heating. If the devices aredesigned to be activated at a temperature lower than the ambient, theymust be kept heated at a temperature higher than ambient. A concept of asingle action arming process, described herein, solves this problem byallowing the devices to remain dormant until usage time. In the dormantstate, the devices are unable to create a path through the shell whenexposed to various temperature environments. Upon arming, they areplaced in an active state after which time they are ready to create apath through the shell once the shape memory material activator attainsa predetermined temperature. This concept allows either the supplier orthe user of the devices to arm them at anytime after their fabricationis completed. Arming, as defined herein, is the process of placing thedevice in an active state of readiness that enables the shape memorymaterial activator to create a path through the shell once it attains apredetermined temperature. Prior to arming, the shape memory materialactivator can attain any temperature, and change phases accordingly,without being able to create a path to release the substance containedin the shell. Enabling is achieved by deforming the shape memorymaterial activator in situ while in the martensitic state. Arming isperformed with a single action involving one simple operation such aspushing, pulling, rotating, or bending. A second arming method involvesthe deformation of the shape memory material activator as well, but inaddition it allows its coupling with the shell. In either case, theability to arm the individual devices at any time before they are placedin service allows for their transportation and storage at anytemperature. In the unarmed configuration there is no need to keep thedevices below or above a specific temperature (refrigerated or heated)in order to avoid premature release. Besides the freedom of maintainingthe devices at ambient temperature, this concept allows the user to setthe release temperature, for a given shape memory material, bycontrolling the amount of deformation during arming that in turncontrols the A_(s) temperature. Of course, it is understood that aminimum amount of deformation is required to create a sufficiently largerecovery force to create the path through the shell wall. In addition toarming substance release devices, the arming concept can also be used toplace other devices in an active or inactive state.

FIG. 149 illustrates a concept of an arming device 3,000 in which theshell is armed by simply pushing the two ends (top and bottom) together.The arming device 3,000 comprises a shape memory material spring 3,002in a stress free and undeformed state, a shell 3,010 containing asubstance and, an inner 3,004 and outer 3,006 frame with integral workenablers. The work enablers are similar to the ones described earlierthat provide gripping and frictional means. In the present example theyare configured as fins. The shape memory material spring 3,002 isallowed to expand and contract freely with fluctuations in temperatureand to transform from one phase to another without undergoing shaperecovery. The shell 3,010 can contain any substance. The two frames3,004 and 3,006 are inserted inside each other and the orientation oftheir fins allows them to slide towards each other irreversibly. Theframes are forced to overlap over a distance that will engage their finsbut will not apply any stress to the shape memory material spring 3,002.In this position the device 3,000 can be maintained indefinitely at anytemperature without the risk of releasing the substance prior toplacement in service. Arming takes place by compressing the ends of thetwo frames, forcing them to slide past each other to deform the shapememory material spring as shown in FIG. 150. A stop 3,008 incorporatedon the inner 3,006 frame allows for a maximum predetermined amount ofdeformation. Arming must take place while the shape memory materialspring is in the martensitic state. Once armed, the device can be placedin service to release the substance contained in the shell 3,010 whenthe shape memory material spring undergoes shape recovery with risingtemperature. Due to the interlocking nature of the fins, the forcegenerated during shape recovery is insufficient to separate them. Itforces the inner frame that forms part of the shell to fail structurallyand create a path through the shell wall to release the substance asshown in FIG. 151. The path may be created in a predetermined separationjoint, a weakened location or where the stresses attain their maximumvalue. Design means such as separation joints, material strength andreduced cross sections can be utilized to direct the path creation to aspecific location. In addition, the path may be created by converting ashell to a permeable one by either stretching or unfolding, in whichcase, there is no need for the shell to fracture or separate. The framescan have any general shape that will allow them to slide past eachother, such as round or square telescoping tubular shapes, or a multipost type structure.

FIGS. 152 to 154 illustrate alternative embodiments of FIG. 149. FIG.152 Illustrates an arming device 3,025 with multiple shells 3,027arranged parallel to each other. The shells release their substancessimultaneously upon activation of the shape memory material spring afterarming. Path creation takes place instantaneously across all shells.FIG. 153 Illustrates an arming device 3,050 with multiple peelableshells. The path creation takes place by attaching the tab 3,052 of thepeelable layer to the separable portion of the frame. When this portionof the frame is forced to separate and move away, it pulls the tab 3,052with it and peels the peelable layer of the shells away to release theirsubstances sequentially. FIG. 154 Illustrates an arming device 3,075incorporating a witness window 3,082 in the outer frame to view a colorchange indicating the shape memory material has been deformed by thepredetermined amount. The color change is produced when the device iscompressed sufficiently for the two frames to overlap to the point thata color dot 3,084 placed on the inner frame aligns with the witnesswindow. The witness window is useful for single temperature settings.For multiple temperature settings, a colored or graded strip indicator3,078 can be employed. These indicators can be mounted directly on thetwo frames or indirectly on separate posts, as shown in FIG. 154.

Work enablers, such as fins that resemble featherboards, can be replacedwith other means to restrict movement in one direction. Such means aresimilar to the ones used in the shape memory material activatedtransport devices that allow one way movement of thermally powereddevices on tracks. They include ratchet gears with detents, balldetents, surface characteristics such as preferentially orientedfeatures, one way rotating wheels and the like. These means relyprimarily on mechanical locking, frictional and adhesion effects betweenthe contact surfaces of two frames. One of the advantages of utilizingratchet gears is that that the number of sound “clicks” produced duringsetting can be indicative of the temperature setting.

The same basic means, in a rearranged configuration, can be used to armthe device by pulling the two ends apart instead of pushing themtogether. This alternative concept is shown in FIG. 155 where the finsof an arming device 3,100 are oriented in the opposite direction to thefins of the device illustrated in FIG. 149. This allows the frames tomove only in one direction, away from each other. In this concept,gripping and locking elements employed in the “push” type device arereversed to allow deformation of the shape memory material spring by atensile force and prevent the reverse movement. Path creation isachieved by the compressive stress applied to the frames and to theshell that is generated during the shape recovery process, The substancecan be released by any of the modes presented earlier such as fracturingof the shell, conversion of its walls to a permeable walls, or removalof a peelable layer. In the example shown in FIG. 156, the path iscreated by crushing the shell. Again, path creation can be directed to aspecific location by employing design means similar to those mentionedabove. In the pull-arming concept, the maximum amount of stretch of theshape memory material spring can be controlled by latch type restrainingmeans. As an example, the increased diameter at the end of rod 3,104serves as a stop once it reaches the hole of the restraining element3,102.

Arming can also be achieved by rotating the frames relative to eachother. FIG. 157 shows an example of an arming device 3,150 where the twoframes engage each other with threads 3,156. To avoid twisting the shapememory material spring due to friction generated by the ends of theframes, free rotating plates can be placed at the top end 3,152 and thebottom end 3,154 of the frames. To assure irreversibility of movement, aratchet-detent gear can be placed between the inner and the outerframes. Again, the number of “clicks” can be indicative of thetemperature setting. The rotating concept has the advantage of allowingfor fine temperature setting when the frame members are engaged withfine threads. Fine threads produce small vertical movement per turn,thereby allowing for precise deformation of the shape memory materialspring. As with the previous concepts, the rotating arming concept canbe used to deform the shape memory material spring by stretching it orshrinking it. Rotary arming can also be accomplished with other rotarymeans besides threaded couplings.

The work enablers, that provide gripping and locking action, do not haveto be placed on the frame sides. FIG. 158 shows an example of an armingdevice 3,200 in which arming takes place by pushing the ends of an inner3,204 and an outer 3,210 frame together and locking them in positionwhen the gripping element 3,208 is inserted into the locking element3,206 as shown in FIG. 159. The shell is contained within the innerframe and during shape recovery of the shape memory material spring3,202 the frame and the shell fracture and a path is created for thesubstance to be released as shown in FIG. 160. Instead of fracturing,the path can be created by stretching the shell to convert its walls topermeable ones, by peeling a peelable wall or by any other method thatcan result in path creation by the application of an external force onthe shell.

FIGS. 161 and 162 show a concept for an arming device 3,250 used tocreate a path in a peelable shell. Arming takes place by pressing thetwo ends of the device. During the arming process a rod 3,252 with agripping element is employed to engage a locking tab 3,254 that is partof the peeling layer while the shape memory material spring is deformedby compression. During the shape recovery process, the shape recoveryforce separates the inner frame's top and creates a path to release thesubstance by pulling the peeling layer 3,258 away from the shell 3,260.Instead of a single substance, multiple substances can be released ifthe shell is compartmentalized to smaller shells that are peeledsequentially with the same peelable layer.

There are cases, such as the ones where the frame parts are heldtogether by friction, that do require the separation or the fracturingof the frame. In these cases, the shape memory material spring must staydeformed to the degree that shape recovery forces would be able toovercome the frictional forces and begin to move the two frames apart.For low pull forces, alternative gripping means such as fastening tapeof loops and hooks can be used. In addition, other gripping means suchas magnets can be used to replace the gripping element and the engagingtab. The rotating arming device can also be used with the peelableshell. In this case, the gripping element and the locking tab may bereplaced with threaded parts (fastener and nut respectively) such thatsimultaneous engagement is achieved between the frame members andbetween these two parts during rotary arming. As with all the devicespresented above, alternative one-way movement means and temperatureindicators can be employed with peelable shells.

Mechanical arming can be achieved manually using finger pressure, handtools such as pliers or automatically by a machine such as a press. Thefirst two methods offer the advantage that the user can arm the devicesin the field without the need of automated machines. The third methodoffers the advantage that devices can be armed individually or in groupsand it is mostly conducive to mass arming. In all methods, armingtakes-place with a single action such as push, pull or rotation.

The basic concept of arming, can also be used as a force release device.FIGS. 163 and 164 show a force release device 3,300 prior to and afterreleasing a tensile force, respectively. This device is similar todevice 3,000, except without the shell, as illustrated in FIG. 149. Inthe armed configuration, the device is capable of withstanding a tensileforce, shown with arrows in FIGS. 163 and 164, of a given magnitude.During shape recovery, the shape memory material spring expands andgenerates a tensile shape recovery force internal to the device. Theshape recovery force together with the externally applied force iscapable of separating the device at a predetermined location andreleasing the externally applied force. In essence this device acts as amechanical fuse. By arming the device to different levels i.e. deformingthe shape memory material spring by different amounts, the shaperecovery force can be varied thereby allowing for release to take placeat different magnitudes of applied forces. However, the amount ofdeformation influences the release temperature and, as such, the devicebecomes a temperature dependent force release device. The same conceptused to release a tensile force can also be used to release acompressive force by simply reversing the orientation of the fins. Forcerelease mechanisms as presented herein are useful for many purposes: (1)Create a path by impact to release a substance. The force releasemechanisms can be incorporated in mechanisms such as those illustratedin FIGS. 80-83 for instantaneous release of a substance. (2) Improve thetemperature release accuracy by controlling the amount of shape memorymaterial deformation in the martensitic state for each individualdevice, thereby removing the uncertainties associated with chemistryinconsistency and processing variables. (3) Create the path to releasethe substance at a single temperature instead of a slowly developingforce with increased temperature. In addition to mechanical fuses, thesame devices can be used to activate or deactivate other devices at apredetermined temperature once they are armed. This is accomplished byutilizing the displacement and the associated force of separation topush, pull or turn a switch or to engage or disengage two mating partssuch as of an electrical connector.

An alternative temperature dependent force release device 3,350, withenhanced capabilities, is shown in FIG. 165. This device 3,350 utilizesthe thermally driven track device to release a force. The tensile forceto be released is applied to thermally powered device 3,352, whoseforward end advances on the track 3,354 during one half of thetemperature cycle when the shape memory material spring expands. Duringthe second half of the temperature cycle, the shape memory materialspring contracts with the aid of the bias spring and the aft end of thethermally powered device 3,352 attempts to advance forward. The degreeof advancement depends on the magnitude of the applied force. If the sumof the applied force and the reverse recovery force, as determined bythe shape memory material and the bias springs, do not exceed the loadcarrying capability of the device, the aft end will move forward.However, if the load carrying capability of the device is exceeded thetrack will separate in a predetermined, structurally weakened, locationand release the applied force. One of the advantages of this device isits capability to act as a thermally activated turnbuckle to link twoobjects together with a force and increase the magnitude of the forcewith temperature cycling until a maximum safe value is reached, at whichpoint the force is released. A compressive force can also be released bysimply reversing the orientation of the fins.

Arming examples so far have demonstrated the ability to arm a device bya single action that consists of the application of a tensile orcompressive force or torque resulting in relative linear or rotarymotion between parts of the device. FIG. 166 illustrates an embodimentof an arming device 3,400 in which the two parts of the frame 3,404 arepivoted at one end while the other ends are free to rotate about thepivot. One part of the frame holds the shell 3,408 that has a tab with alocking element 3,410 attached to it while the other part has a grippingelement 3,406 attached to it. A shape memory material spring 3,402 isattached to both parts of the frame that can be deformed when the twoparts are rotated towards each other. If the pressing continues, the twoparts of the frame 3,404 lock together when the gripping element 3,406is inserted in the locking element 3,410. When the shape memory materialspring is compressed in the martensitic state, the device is armed andready to release the substance contained in the shell when the shapememory material spring 3,402 is heated and undergoes shape recovery.During shape recovery, the shape memory material spring expands, forcesthe frame parts to counter rotate about the pivot, and creates a path torelease the substance. Release takes place as the gripping element 3,406pulls the tab with the locking element 3,410 and applies a force to theshell. This force results in the path creation by fracturing the shell,tearing it, peeling it, converting it into one with permeable walls andthe like.

Single action arming is not limited to the methods of compression,tension and rotation. Other methods easily adaptable by the user of thedevice can be employed. In all cases, the objective is to deform theshape memory material during the arming process while it is in themartensitic state. One of these methods is to reposition the shell inthe device at the time when the service life is to begin and at the sametime deform the shape memory material spring in the martensitic state bya single action. The ability to reposition the shell at any time hasseveral advantages: (1) Eliminates the need to transport and store thedevice at a safe temperature either by refrigeration or heating. (2)Permits the interchange of devices and shells. (3) Makes the devicereusable. The third item is achieved by re-deforming the shape memorymaterial at the martensitic state during the re-arming process.Re-arming is adaptable by many of the concepts described herein. FIG.167 shows a single action arming device 3,450 where pressing on a shell3,456 repositions it in the device and deforms the shape memory materialspring 3,452 by bending it over a mandrel 3,454. FIG. 168 shows theshell in the new position after arming. The shell can be held in placesecurely by such means as adhesives pre-placed on the bottom of thedevice, interference fit, or frictional means 3,458. The shell is heldin place prior to arming by similar means. In addition, a seal 3,460that breaks during the arming process can be incorporated to assure theintegrity of the device. The shape memory material spring in this caseis either in a wire or strip form that is deformed at the martensiticstate during the insertion of the shell. During shape recovery, theshape memory material spring straightens out and creates a path throughthe wall of the shell by puncturing it, as shown in FIG. 169, to releasethe substance. By varying the radius of the forming tool, the amount ofdeformation and in essence the A_(s) temperature, can be varied.

An arming concept utilizing a deformable shell with the shape memorymaterial inside the shell is shown in FIG. 170. In this concept a device3,470 comprises a shape memory material spring 3,472 in the form of awire or strip located inside a deformable shell 3,474. One end of theshell is fixed while the other one is free and contains frictional means3,476 consisting of surface features such as fins or knurling marks thatallow it to bend in one direction only and lock in position when it isrotated around an arc 3,480 containing similar frictional means 3,478.The different types of frictional means presented elsewhere areapplicable in this case also. Prior to deformation, both the shell andthe shape memory material spring have a straight shape and both aredeformed simultaneously while in the martensitic state by a singleaction arming process of bending. The shell is restrained from movingback by the frictional means 3,476 and 3,478 as shown in FIG. 171.During shape recovery upon heating, the shape memory material springattempts to recover its shape, while the shell is locked in place, andin the process creates a path through the shell wall by puncturing itfrom the inside to release the substance as shown in FIG. 172.

An alternative arming concept that utilizes a device 3,500 with afoldable shell 3,504 and a shape memory material spring 3,502 locatedinside the shell is shown in FIG. 173. The shell is prevented fromexpanding by the guide rods, but it is allowed to shrink whencompressed. FIG. 174 shows the device 3,500 in the armed configuration.Arming of the foldable shell 3,504 is performed by compressing the shelland the shape memory material spring 3,502 simultaneously. Part of theshell may contain a compressible fluid to allow for volume reductionduring arming. During compression, the ends of the folds are locked toprevent reversal of the deformation. A temperature indicator can beinstalled on the outside to indicate the release temperature based onthe induced amount of deformation. During shape recovery, the shapememory material spring 3,502 expands, but the shell 3,504 is restrainedfrom complying and the shape recovery force creates a path through theshell walls to release the substance. The resulting path can be afracture in the shell as shown in FIG. 175, or conversion of the end ofthe shell to a permeable one by stretching. An alternative armingconcept for the foldable shell is to place the shape memory materialspring outside of the shell such that the two are in series.

The thermally powered device can be armed by a single action to becomeactive with temperature cycling of the shape memory material spring insimilar manner as the rest of the devices as shown in FIG. 176. Thisfigure shows a thermally powered device 3,550 comprising a grippingelement 3,552 and a locking element 3,554 that are incorporated in thevariable length body 3,556 and the bias spring 3,558, respectively. Oneend of the bias spring 3,558 is attached to the one end of the variablelength body while the other end remains free. The shape memory materialspring 3,560, housed inside the variable length body, is attached toboth ends of the body. In the unarmed state, the shape memory materialspring is longer than the bias spring. During arming, the ends of thedevice are compressed along with the shape memory material spring 3,560.During this process, the gripping element 3,552 is inserted into thelocking 3,554 element, both elements are locked together, and the freeend of the bias spring becomes permanently attached to the end of thevariable length body.

The thermally driven track device can also be armed by a single actionto become active with temperature cycling. In this case, the beginningend of the track 3,584 of the thermally driven track device 3,580, shownin FIG. 177, contains no work enablers or frictional means. Thethermally powered device 3,582 in this location expands and contactswith temperature cycling of the shape memory material spring but thereis no traction to allow it to advance forward. Arming takes place bysimple pushing the thermally powered device 3,582 to engage the fins ofthe track 3,580 a shown in FIG. 178 and begin the forward advancement.This method can also be used at the other end of the track when thetravel of the thermally powered device is completed. In order to avoidhaving the thermally powered device apply a force to the end of thetrack or come out of the track if no barrier exists, elimination of asegment of work enablers or frictional means from the end of the trackwill keep the thermally powered device inside the track with no tractionand unable to move out. This is a de-arming process that basicallyrenders the device inactive.

A shape memory material based substance release device with a biasspring has the ability to produce a displacement during temperature risefrom A_(s) to A_(f) and recover it with its from M_(s) to M_(f).Depending on the type of shell, this displacement and the associatedconstrained force can be used to create a path (a) with the temperatureof the shape memory material spring either increasing or decreasing or(b) with the temperature increasing and close it with the temperaturedecreasing or vice versa. FIG. 179 illustrates an arming device 3,600comprising a shape memory material spring 3,602 and a bias spring 3,604with a restraining pin 3,606 holding the bias spring in a compressedstate while the shape memory material spring is in the undeformed state.The device 3,600 is armed by a single action, shown in FIG. 180, byremoving the restraining pin 3,606 while the shape memory materialspring 3,602 is in the martensitic state. Upon removal of the pin, thebias spring expands and deforms the shape memory material spring anamount “x” until both springs come to equilibrium. During shaperecovery, the shape memory material spring expands, compresses the biasspring and produces a displacement “y”, shown in FIG. 181. Duringcooling from the austenitic to martensitic state, the resistive force ofthe shape memory material spring decreases and the bias spring is ableto compress it an amount “−y”. When the displacement “y” is constrained,a force is produced that can be utilized to open either a permanent pathin a shell to release the substance contained in it or to open and closea path with temperature cycling for a repeated release. The two springscan be placed either in series or parallel to each other. Alternatively,the restraining pin 3,606 can be pushed in, or it can be replaced by amechanical switch. This device is adaptable to many types of single ormultiple release shells and can incorporate more than one shell as shownin FIG. 78. Advantages of this device include ease of arming andprevention of tampering, as the pin can not be re-inserted once the biasspring has been released.

An alternative arming concept for a device that releases a substancewith the fall of the temperature of the shape memory material spring isillustrated in FIG. 182. In this concept the device 3,650 is armed by asingle action of pressing the two ends together, similar to the deviceillustrated in FIG. 149. The device 3,650 comprises a shape memorymaterial spring 3,660 and a bias spring 3,652 in series, with aninterface plate 3,658 between them. A gripping element 3,656 mounted onthe interface plate 3,658 engages a locking element 3,654 mounted on theinside surface of the inner frame during the arming process. In thisprocess the shape memory material spring 3,660 is compressed, as shownin FIG. 183, while in the martensitic state. With a rise in temperaturethe shape memory material spring 3,660 undergoes transformation,expands, compresses the bias spring 3,652 and engages the gripping 3,656and locking 3,654 elements together, FIG. 184. With a fall intemperature the shape memory material spring 3,660 undergoes reversetransformation and shrinks as the bias spring 3,652 expands. During thisprocess the interface plate 3,658 that holds the gripping element 3,656withdraws and pulls the locking element 3,654 along with it. The lockingelement 3,654 is attached to the peelable layer 3,662 of the shell andpeels it away, as shown in FIG. 185, creating the path to release thesubstance.

The single action arming concept is not limited to manual or mechanicalarming. It can be extended to other single action methods such ashydraulic, pneumatic, electric, and magnetic. FIG. 186 illustrates ahydraulic arming device 3,700 that utilizes a flexible liquid fluidreservoir 3,710 to deform a shape memory material spring 3,708 in themartensitic state. This is accomplished by pressing on the reservoir andforcing the fluid though a one way outward flow valve 3,714 into acylinder 3,704 through a connecting tube 3,718. The fluid pressureforces a piston 3,706, that is configured with a locking element on itsfront end, to move forward. As the piston 3,706 moves forward, itstretches the shape memory material spring 3,708 that is attached to itsback end. This movement stretches the shape memory material spring andforces the locking element to engage the gripping element 3,720 attachedto the tab 3,702 of the peelable shell. The device 3,700 in the armedposition is shown in FIG. 187. During shape recovery, the shape memorymaterial spring contracts, draws the piston with it and forces the fluidback into the reservoir through a one way inward flow valve 3,712connected to the cylinder with a tube 3,716 and creates the path torelease the substance by peeling the peelable layer of the shell. Thedevice 3,700 with the path created is shown in FIG. 188.

The gripping process can produce an auditory signal (similar to asnapping action) that would be indicative of the completion of thearming process and can be utilized as a verification of the engagement.The number of sounds (“clicks” or “snaps”) can be indicative of thedegree of shape memory material spring deformation and the releasetemperature setting. This type of gripping verification applies to allmechanisms utilizing such engagement grips. Other advantages of thisarming process include: (1) Faster activation in response to a changingoutside temperature as the fluid surrounding the shape memory materialspring acts as a heat transfer medium. (2) The tubes connecting thedevice with the reservoir can be of any length such that arming can takeplace remotely.

The hydraulically arming device can also be used to arm shells thatcreate and close a path with temperature cycling when a bias spring iscoupled with the shape memory material spring. Once the device is armed,the fluid flows in and out of the reservoir with temperature cycling asthe piston oscillates back and forth. Optionally, the fluid can bedrained out after the second half temperature cycle instead of returningto the reservoir. Hydraulic arming is not limited to peelable shells.Other types of shells whose path can be created with the application ofan external force can be incorporated in this device.

The hydraulic arming concept of FIG. 186 can be adapted to arm a devicemechanically by using a flexible mechanical elements such as cablerelease systems to apply pressure to the piston and advance it to engagethe gripping element. In addition the cable may, upon completion ofexpanding the shape memory material, engage it with a bias spring toallow the device to release a substance repeatedly with temperaturecycling after it is armed. As with the hydraulic arming, the cablerelease constitutes a single action arming process.

Instead of hydraulic arming, the same device can be armed pneumatically.A gas, like air, can be used for this process. The gas can be suppliedunder pressure by a reservoir or it can be pumped atmospheric air.Advantages of gas arming are that the reservoir used for hydraulicarming can become a gas reservoir or it can be replaced with a manuallyoperated air pump. In either case, the gas does not have to be collectedback during shape recovery.

FIG. 189 illustrates an alternative arming device 3,750 that utilizesvacuum for the arming process. This device 3,750 comprises amechanically arming device 3,752 similar to the one illustrated in FIG.149 whose inner and outer frames constitute telescoping tubes and ahousing 3,754 sealed around the bottom of the outer frame that containsan opening. Arming takes place by pulling vacuum through the opening ofthe bottom of the outer frame. During this process, a pressuredifferential is maintained between the volume defined by the spacebetween the exterior of the device 3,752 and the interior of the housing3,754, and the volume defined by the interior space of the device 3,752.This pressure differential forces the inner frame of the device 3,752 toslide down, compress the shape memory material spring and arm thedevice. The two frames of the device 3,752 are engaged with fins on theinner side and surface roughness on the outer side to aid thedevelopment of the differential pressure. The advantage of this conceptis the ability to arm multiple units by single action, in their storageor transportation containers, by pulling vacuum directly through thecontainers. For individual arming, the housing can be eliminated andvacuum can be pulled from the opening of the bottom of the outer frame.In this case, the arming differential pressure exists between ambientatmosphere and the inner volume of the device.

In addition to the methods mentioned above, a magnetic force can also beutilized to arm the device 3,800 by a single action as illustrated inFIG. 190. The device 3,800 is similar to the one illustrated in FIG. 149with magnetic material 3,802 attached to the bottom of the inner framesuch that when the bottom of the device is in close proximity to amagnet, the attractive magnetic force pulls the upper frame downward andarms the device. The magnetic material can be incorporated in the deviceby several methods such as separate parts attached to it, plated on itscomponents and the like. For mass arming, a large magnetic table can beused to arm the units inside their storage or transportation containersprovided the units are properly oriented and the container constructionmaterials do not interfere with the magnetic forces.

Optionally, all devices can be armed by electrical energy sources. Suchsources include batteries and electric power. Electric arming has theadvantage that it eliminates the need for manual arming, especially incases where either a substantial force is required or manualaccessibility does not exist. For arming to take place, the electricenergy must be converted to other forms of energy such as mechanical ormagnetic to produce a force along with motion to deform the shape memorymaterial spring. With the addition of microprocessors, fine motioncontrol can be achieved that can result in increased arming precision.Single action arming with electrical energy involves a simple operationsuch as pushing a button. The push of a button may activate anelectromagnet, such as a solenoid, to apply a force and arm one or moredevices.

In addition to single action arming method, a multi-action method can beadopted to arm the devices. This method typically involves two or moresequentially and separate operations such as the bending of the shapememory material spring and its installation of it in the device. Such aconcept is illustrated in FIGS. 191 to 195 where, as part of the armingprocess, the device is armed by coupling the shell with the shape memorymaterial spring. In this concept the shell is in the form of a hollowstraight cylindrical shape as shown in FIG. 191. The core opening of theshell is large enough to accommodate a shape memory material spring inthe form of a wire or strip. The initial austenitic shape of the shapememory material is curved, FIG. 192. It is deformed to a straight shape,FIG. 193, in the martensitic state and loaded into the shell, FIG. 194.During shape recovery, the shape memory material spring goes back to thecurved shape and, in the process, creates a path (single or multiple)through the shell wall to release the substance, FIG. 195. One of theadvantages of this concept is the ability to mix and match shape memorymaterial springs of various A_(s) temperatures with shells containingdifferent substances. In addition, the release temperature can beadjusted by deforming the shape memory material springs to variouslevels.

Devices incorporating the arming concept can become reusable. Fordevices whose path creation is permanent, a new shell must be insertedafter each release. Reuse of the device provides the advantage of havingto replace only the shell or its contents and avoids the expense ofusing a new device each time.

Besides the spring presented herein, other springs configurations can beused to arm the device and create a path through the shell wall. “ASMEY14.13M (ANSI Y14.13M-1981) Mechanical Spring Representation” presentssprings that can be used for this purpose. Any shape memory material ofany configuration that can produce work during temperature change iscapable of being used as an activator to create a path though a shellwall.

The release accuracy of the devices can be improved by fine-tuning thearming process. This might be necessary due to of the large influence ofchemical composition and processing parameters on the shape recoverycharacteristics of the shape memory materials, especially thenickel-titanium based alloys. Major influencing processing parametersinclude cold work and heat treating. Shape recovery characteristicsinclude transformation temperatures and shape recovery forces.Fine-tuning involves certain adjustments that result in a consistentpath creation temperature with the minimum required force within thesame lot or different lots of materials. It also allows for a “dial-in”path creation temperature for an individual device. Fine-tuning isaccomplished by the methods described herein but it is not limited tothese methods.

The first fine tuning method is the arming process itself. It controlsthe shape memory material spring deformation, which in turn controls therelative position of the A_(s) to A_(f) curve, and, in general, thehysteresis curve with respect to temperature. The greater the induceddeformation, the greater the shift of the curve to higher temperatures,resulting in increased release temperatures. Typically, once deformationexceeds a certain level, the width of the hysteresis begins to expand,usually by shifting the A_(s) to A_(f) portion of the curve to highertemperatures. With this method, inconsistencies in the shape memorymaterial behavior can be minimized among the different devices. Further,the shape recovery forces, required to create the path, increase withdeformation but tend to level off above a certain level that is of theorder of 1.5% strain and begin to slowly decrease above 8%. This way,deformation above a minimum level produces consistent path creationforces while shifting the release temperature to higher levels. However,the variation of the shape recovery force is not important as long asthe minimum force required to create the path and release the substanceis generated.

The second fine tuning method is the control of the temperature aboveA_(s) at which the shape recovery force begins to develop. Ignoringcompliance factors that tend to be device specific, this temperature iscontrolled by the gap or the slack allowed between the deformed shapememory material spring and the shell. This can be the gap between theshape memory material spring and the shell in the case that pathcreation takes place by expansion of the shape memory material spring,or the extra tab length allowed on a peelable shell. FIG. 196 shows anexample of device 3,850 in the unarmed state with a peelable shell 3,852mounted on a round substrate 3,858 and a shape memory material spring3,856 inside a housing 3,854 that is capable of rotating in onedirection along the circumference of the substrate via a ratchetmechanism (not shown). FIG. 197 shows the device 3,850 in the armedstate with the shape memory material spring 3,856 in the martensiticstate. Arming can take place with any of the methods presented in thisdocument. Arming results in expansion of the shape memory materialspring 3,856 and increases the slack that exists in the length of thetab 3,860. Fine tuning involves the rotation of the housing assembly,FIG. 198, from position A-A to A′-A′ such that a calculated amount ofextra tab 3,860 length remains behind. Once shape recovery begins, theshape memory material spring will begin to contract but will not exert aforce on the shell until all the slack is taken up and the tab is snug.It is at this temperature that the shape recovery force will begin todevelop and start the path creation process and release of thesubstance, FIG. 199. While the first method controls the position of thetransformation temperature curve, the second method controls thetemperature at which release takes place within the transformationcurve. The sequence of the two methods is interchangeable.

An alternative fine tuning method consists of a combination of the firstand second method. This involves the adjustment of both the amountdeformation induced in the shape memory material and the length of thedeformed section. It is applicable to devices, similar to the onesillustrated in FIGS. 4 and 14, where a shape memory material hook isused to restrain a non-shape memory material containing storedmechanical energy. Fine tuning of the release temperature is achieved byvarying the bend radius of the hook of the shape memory material springand/or the arc length of the hook. Another alternative method,applicable to the force limited release systems similar to the oneillustrated in FIG. 88, consists of varying either the bias angle of therestraining non-shape memory material leaf spring and/or its length. Alarge angle requires larger recovery forces for release and therebyhigher release temperatures. Also, a longer length, results in higherrelease temperatures.

Release of Substances

All devices presented herein are capable of releasing substances thatcan stimulate the senses; vision, smell, taste, touch and hearing or beundetected by the senses. Applications for release of visible substanceswas described earlier under temperature indicators. Applications forrelease of substances that stimulate the rest of the senses aredescribed in this section. Typically, any released substance may bedetected by more than one sense and release of a single substance mayeffectively serve multiple purposes.

Any of the devices described herein are capable of releasing a substanceto produce an odor. This odorous substance can be of any type, fromobjectionable to fragrant. When used in temperature warning devices, theodor may be objectionable to indicate that a safe temperature limit hasbeen exceeded. The device may release the odorous substance directlyonto the product that it is protecting. The product may be a type offood such as ground meat that has been exposed to an unsafe temperature.Release of the substance effectively transfers the source of the odor tothe product and renders it unusable. Alternatively, the substance can bereleased into a reservoir. Release of the substance can also take placewhen a sensor, such as a biological one, detects increased orundesirable microbe activity and commands the release of the odoroussubstance. In this case, activation requires an external heat sourcesuch as a battery to provide the necessary heat to activate the shapememory material. When the odorous substance is released on a product,olfaction based devices not only act as warning devices, they also actas decision makers and inspection devices determining productacceptability and assuring that a rejected product can not be used. Whenreleased into a reservoir, the wall of the reservoir must besufficiently permeable to allow the volatile odor compounds to permeatethrough and be released to the surroundings. The release rate can becontrolled through the permeability and physicochemical properties ofthe reservoir wall in relation to the properties of the substance. Inreleasing the substance into the reservoir, the osmotic principle can beused to restrict the flow direction across a surrounding membrane andavoid dilution of the substance inside the shell. Optionally, thesubstance may be combined with another substance in the reservoir toproduce a new odor. If the release rate of the substance into thereservoir is continuous, the type and strength of released odor willchange with time due to continuous change in the mix ratio of the twosubstances.

The release rate of the odor can be controlled either by thepermeability of the reservoir walls or the substance can be contained ina permeable or semi-permeable membrane within the shell, such that whenthe path is created through the shell wall, the substance, and inessence the odor, is released through the membrane. Further, thesubstance can be pressurized in the shell to provide additional meansfor release rate control. Use of time dependent and time-temperaturedependent release devices to release odor-producing substances enhancesthe capabilities of the olfactory devices. The release can be integratedonce a predetermined temperature is exceeded such that the odor changesin strength and type with either time alone or time and temperature. Thefeatures of vision and olfaction based temperature warning devices canbe combined to produce one device that would provide a dual indication,a color change and odor. This is achieved by the release of an odoroussubstance that is also a dye. The reservoir to which such a substance isreleased must have a transparent window for the color detection and partof its wall must be sufficiently permeable to allow the odorant'svolatile compounds to be released to the environment. Control of thepermeability and the release area of the wall provide more degrees offreedom to control the release rate of the odor.

Temperature activated olfaction based devices can be used as fire alarmsto provide a warning once a predetermined temperature is exceeded. Inthis concept, the shape memory material creates a path through the shellwall to release a substance containing strong and objectionable odorantcomponents. The substance can be released directly into environment werethe odor will be emitted to the atmosphere at a rate controlled by theproperties of the substance and the volatility of the odorous compounditself.

For fire alarms, a characteristic odor can be selected such that upondetection it will be associated with the danger of a fire. When multipleshells are incorporated in one device, the path in the shells can becreated sequentially with increased temperature. As more substances arebeing released, the type and strength of the odor can change to indicatethe increased danger. These devices can be installed in buildings aswall units, in areas where there is a potential for a fire such aselectrical cabinets, on the outside surface of stove hoods etc., and inthe heating and air-conditioning ducts of buildings where the releasedodor can be distributed throughout the building by the re-circulatedair. Temperature activated odorous safety devices have severaladvantages over conventional fire alarms. They are maintenance free asthey can operate without external energy sources such a batteries. Theycan be placed in areas such as the kitchen because they are unaffectedby humidity, steam and volatile products generated by cooking. Sincethey detect temperature, they can be activated and provide a warning byreleasing an odor before there are any combustion products in the air.In addition to being able to replace or complement existing alarmsystems, they offer warning to visually and auditory challenged peoplefor whom present fire alarm systems may not be beneficial.

Olfaction based devices can also be used as fragrance delivery devices.In this capacity, the released odor produces a pleasant scent. Thesubstance can be released directly to the environment, to a reservoirfor mixing with another substance prior to release to the environment,to a mammalian body through a transdermal (patch) device or to anabsorbent material that would further control its release to theenvironment. In all cases, all the devices described herein are capableof delivering the fragrance. However, when the substance is released toan enclosure such as the reservoir mentioned above, means must beprovided to allow the fragrant volatile compounds to be released fromthe enclosure to the surroundings. Such means include permeable orsemi-permeable barriers such as membranes or walls. The transdermal drugdelivery devices, can be used to deliver a fragrance to a mammalian bodywhen the body temperature exceeds a predetermined level. These devicescan be designed to deliver the fragrance to both the environment and toa mammalian body simultaneously. This is achieved by converting part ofthe top layer of the transdermal device into a permeable orsemi-permeable wall. In this case, upon activation of the shape memorymaterial the fragrance is released into a reservoir prior to delivery.If desired, more than one release device can be incorporated in onepatch that would either extend the temperature release range, upwards ordownwards, or complement the fragrance of the others. Alternatively, thetransdermal devices can be used to release the fragrance to theenvironment only but use the body's heat for activation. Transdermalfragrance delivery devices have distinct advantages over manuallyapplied fragrances such as perfumes. They can provide on-demand perfumedelivery once the body temperature exceeds a predetermined level. Theneed for such situations arises during physical activity such asexercise and emotional changes. In addition, they can be placedstrategically in the body to counter any localized sources of odor.Further, they are capable of changing the strength and type of fragrancewith time or with time and temperature.

Instead of being body temperature activated, transdermal fragrancedelivery devices can also be configured to be activated with changes inambient temperature. Simply, the shape memory material is thermallyisolated from the body, by being worn an a piece of clothing, such thatit responds the ambient temperature fluctuations. Since ambienttemperature fluctuates more than body temperature these devices arecapable of producing fragrances of various types and strengths at higherfrequencies as a person moves from place to place.

All the devices with their features described herein can be used asdelivery systems to introduce, enhance and in general alter the taste orflavor of foods and drinks exposed above or below a predeterminedtemperature. These devices can be activated during cooking to releasespice flavors to the food once a predetermined temperature is reachedwithout actually releasing the spice seeds and leaves themselves.Utilizing the same principle, instead of spices the shell may containtea leaves or coffee. The device is immersed in water while it is beingheated and when the predetermined temperature is reached, the shapememory material creates the path to allow the hot water to enter theshell and extract the tea and coffee flavor. Using the reversible shell,the path is closed once the temperature drops below a predeterminedlevel thereby stopping the extraction process to avoid extractingunpleasant flavors. For repeated usage, the devices can be modified toallow the opening and closing of the shell to insert new substances.

In addition to being used as gustation delivery systems, these devicescan also be used as taste alarms to alert one that the a food producthas exceeded a predetermined safe temperature. Taste can be altered bydirectly releasing a substance that may be safe for consumption butrenders the food uneatable due to its objectionable flavor, texture orother attributes intolerable by the sense of taste. In addition, thesubstance in these alarms can be combined with odor generatingsubstances and or dyes to provide a double or triple alarm. Food anddrink alarms that stimulate the sight and especially the smell and tastesenses are useful for the general population and provide a great benefitto children whose instinct of safety is not well develop, to elderly andmentally challenged people that can not rely on visual means or slightlyaltered taste to determine food safety.

Any shape memory material activated device based on the conceptspresented herein is capable of releasing substances that can beperceived by the sense of touch. Such devices, among other things, canbe used as warning devices for food and pharmaceutical products. Once apredetermined temperature has been reached, the shape memory materialcreates a path though the shell wall to release a tactile substance thatserves as an indication that the product has been exposed to an unsafetemperature. Release substances can be of any type that can be felt bytouch and act as warning indicators. Preferred candidate types ofsubstances include the ones that will drastically alter the touchfeeling of the product container. Candidates include substances such asadhesives that will produce a sticky feeling, greases that will producea slippery feeling. The released substance, in addition to beingtactile, may contain ingredients to provide visual, olfaction andgustation indications.

In all substance release device concepts presented herein, auditorymeans can be incorporated to generate an acoustic signal upon release ofthe substance. This feature complements the stimulation of the sensesused to detect the release of the substance such as vision, smell, tasteand touch. This feature is incorporated by utilizing stored mechanicalenergy to release the substance. With this concept, the shape memorymaterial releases an elastically deformed spring whose stored mechanicalenergy is used to create the path by applying an impact force to theshell. During the path creation process, upon impact with the shellwall, a “snap” type auditory signal is produced that can be utilized asverification process. Besides the concepts in which stored mechanicalenergy is utilized to create the path, other devices are capable ofproducing an acoustic signal upon release of the substance. They includedevices with brittle shells and/or shape memory materials whose shaperecovery curves have a steep slope such that shape recovery takes placewithin a narrow temperature range. Narrow temperature ranges effectivelyresult in the rapid generation of shape recovery forces that can produceauditory signals especially when they fracture brittle shells. Anotherway to produce a auditory signal upon release of a substance is to sealthe contents of the shell in vacuum or to pressurize them. During thepath creation process a “popping” sound will be generated, as thepressure equilibrium is achieved, indicating the initiation of therelease process.

Release of sense stimulating type substances once a predeterminedtemperature is attained can be extended to toys that encompasses many ofthe perceptible substances. A doll can be made to cry or perspire once apredetermined temperature is reached. This is achieved by incorporatingshape memory material activated devices to release substances thatsimulate sweat, tears or other bodily substances. Each substance canhave its own color, smell, taste and touch feeling to resemble reality.The path creation can take place though valves resembling the tearglands in case of crying simulation or the though permeable walls incase of sweat.

Any number of substance release devices presented herein can be groupedtogether to perform as a system and to produce a combined effect.Devices performing collectively as a system have the capacity to produceresults different and of a larger scale that no single device by itselfcan produce. The systems behave differently than their individualcomponents. The release temperatures of the individual devices can beselected such that the system as a whole will produce any releaseprofile with respect to either time, or time and temperature. The systemmay be designed to begin releasing at temperature “A” and finishreleasing at temperature “B”. However, the release rate can be keptconstant within the “A”-“B” range or it can be variable. In addition,the system may be designed to release substances at more than onetemperature range such that a group of devices may be activated within atemperature range of “A”-“B” and another group within a range of“C”-“D”. One temperature range may encompass the other, the two rangesmay overlap or they may be distanced such that there is no releasebetween them. There is no limit to the number of devices that canparticipate in a group or groups to form the system. This is truly aflexible and variable scale release system. It can consist of any numberof release devices, of any type, with each shell containing the same ora different substance. The substances released by an individual deviceupon activation and path creation may change state, such as liquid tosolid, with either direct release to the surroundings or release to areservoir first. Further, the physical distances between devices can bevariable and depend only on the purpose of the system.

Variable scale release systems can be used in either indoor or odorgatherings such as theaters, concerts, sport events etc. Shape memorymaterial activated release devices containing fragrant producingsubstances can be placed in inconspicuous places in the gathering area.Activation of the shape memory material materials and creation of thepaths can take place with a rise or fall of the temperature. Where thereis climatic control such as air-conditioning or heating, release can beprogrammed to coincide with special timings by increasing or decreasingthe temperature. In outdoor gatherings, release will depend on changesin the outside temperature. Different fragrances or combination offragrances can be produced in different sections of the gathering areasimply by selecting the shell substances that would produce the desiredfragrances. Also, different devices can be activated at differenttemperatures to produce different fragrances and to enhance theeffectiveness of the special events. The distribution density of thedevices can be adjusted to produce the optimum fragrance strength for agiven space and population. By combining the release devices withmicroprocessors and a battery for activation, the release time can bepreprogrammed.

The same concept used for the fragrance mass delivery systems can alsobe used to deliver pharmaceutical products such as vaccines,immunizations and in general prophylactic type drugs to large numbers ofpeople. The people may be city dwellers, villagers or military personnelin the battlefield. Large scale drug delivery systems can be used inemergency cases such as imminent chemical or biochemical terroristattracts where the affected population must be immunized as soon aspossible or an antidote or curative drug must be delivered as soon aspossible after such an attract. Besides chemical and biochemicalterrorist or war disasters, the same systems can be used to deliverprophylactic drugs to large populations in other types of calamitiessuch as infectious epidemic diseases having the potential for rapidpropagation. The devices can be used to deliver drugs to largepopulations spread over large areas where there is no time to distributeand administer the drugs by conventional means or no distribution systemexists at all.

These systems can release drugs that are in the gas, liquid or solidstate but volatize and become airborne upon release. The drugs aredelivered to humans primarily by the inhalation process. The shell maycontain means to volatize or atomize the substance upon release tofurther aid the delivery process. The mass delivery drug systems offerthe advantages of being able to produce slow releases over long timessuch that the danger of overdosing are minimized. They can bedistributed at one ambient temperature and be activated at a differenttemperature for optimum delivery and to allow maximum exposure toaffected population. The devices can be distributed by; airplane, launchrockets or other remote launch systems. The devices can be stored andtransported at any temperature and for any length of time as long as theshell contents remain unaffected. They can be armed prior todistribution time i.e. upon dropping from an airplane. If there is rapiddepressurization of the devices at this time, such as when they aredropped from a airplane, it can be used advantageously to arm thempneumatically upon exposure to a lower pressure environment. They can beselected to have different activation temperatures and be able torelease the substance instantaneously, continuously, with changingtemperature or with repeated temperature cycling.

Variable scale release systems can be used as non-lethal weapon deliverysystems. The purpose of these delivery systems is to minimize oreliminate lethality, act as deterrent systems and, in general, toreplace land mines. They offer a substantial improvement over land mineswhose results are probabilistic in nature and are associated with longlasting effects far beyond the end of war conflicts. Their intent is tobe used for such operations as warfare, riot control, containment and todeny ground. These systems are similar to the drug mass delivery systemsand they are distributed by similar means. The main difference is thatthe shell may contain any substance that upon release may discomfort orincapacitate the recipients.

Capabilities and advantages of these delivery devices both individuallyand as a system include: (1) They are not restricted to a particularsubstance. Shells can contain any substance without affecting the devicedesign. (2) They can be stored indefinitely at any temperature withoutthe risk of accidental activation. Since they are maintained unarmed,there are no stressed parts to undergo stress relaxation or creep and,if shape memory material such as Nitinol is used as the activator, thematerial remains corrosion free. (3) The shells can be made of materialthat would degrade with time to release their contents. This providesand added feature to assure that there are no long term effects withthese type of non-lethal delivery systems. (4) Use of multi-releasedevice can extend the release for multiple day-night temperature cycles.

There are multiple applications for systems of substance releasedevices. They include release of substances to remotely sterilize,fumigate, or decontaminate an area or structure. Another application isinsect repellant systems in which case the path is created below acertain temperature (typically in the evening) to release the repellant.A nearly insect free area can be created by placing several devices withpath reversal in strategic locations. Path reversal is required only ifthe devices are expected to function daily at a given temperature.

Drug Delivery

The following is an explanation of some of the applications of theembodiments described herein for use in drug delivery systems. On demanddrug delivery system applications are subdivided into four generalcategories as follows:

(1) A first application is a transdermal system that is activated byrising body temperature. In this application the patch is applied whenfever is anticipated due to upcoming flu symptoms, a disease or a drugside effect etc. However, there is no need for the drug until the feverrises to a critical temperature. With this device, although the patchmay be worn, the drug is not released until the critical temperature isreached. The advantage of this application is the elimination of orallyadministered drugs, elimination of temperature measurement, and the factthat the drug is used only if and when it is needed. More, background,information on transdermal systems is presented below.

(2) A second application involves transdermal systems used to deliverdrugs but not activated by rising body temperature. In this case, thedevice must be activated with an external energy source when the needfor the drug arises. For automatic activation the energy source has tobe stored electrical energy (batteries) while for manual activation heatapplied directly to the device, such as by a hot compress, will suffice.One example of this case is insulin delivered drugs.

(3) A third application involves implantable drug delivery systems.Again, for an automatic operation, a self-contained energy source isrequired. For manual operation an external heat source is required. Inthis case heat is conducted through the body to raise the temperature ofthe shape memory material and activate the device.

(4) A fourth application involves mixing of predetermined quantities oftwo or more drugs. This is a useful application when there is a need tomix two or more drugs without having to measure them. This need mayarise from field work where it is not convenient to measure or when theshelf life of a drug is extended when mixing takes place at the time ofapplication.

Activation Energy Sources

Various energy sources can be used to heat the shape memory material inorder to undergo shape recovery. The choice of energy source depends onthe particular application. For most applications, ambient thermalenergy is the ideal candidate. This includes mostly temperature warningand alarm systems as well a temperature indicators. For all ambientheating applications the heating source can be substituted with othersones such as electric heating. For drug delivery applications thechoices depend on the particular application. Transdermal drug deliverysystems can utilize the body temperature for activation or an externalsource such as batteries. In the second case, a temperature sensor,other than the shape memory material, is required to detect the rise inbody temperature and activate the device. When a separate temperaturesensor is used, the shape memory material acts as the actuator to createthe path and release the drug. For remote heating applications such asin the case of implant drug delivery devices, the primary choices are;body heat, direct application of heat, electric heating, and magneticinduction heating. Body heat can be due to fever caused by ailments orit can be due to induced fever with the objective to activate the shapememory material based implant. Direct application of heat using sourcessuch as hot pads requires the transfer of heat through the body to reachthe shape memory material. Electric heating requires stored energysources such as batteries. Electric heating is achieved by utilizing theshape memory material as a resistor and heating it by passing electriccurrent through it. Magnetic heating of the shape memory material isachieved by conduction from a ferromagnetic material that is heated bymagnetic heat induction. All energy sources used for substance releasedevices can also be used for thermally powered devices, whether they arereleasing a substance or not. Thermally powered devices can also bepowered hydraulically, pneumatically or mechanically without theincorporation of a shape memory material activator.

For greater flexibility, a more accurate temperature activation system,and better time response, the shape memory material, coupled with aseparate temperature sensor and the appropriate controls to activate thedevice, can be used as the means to generate the force to fracture theshell. Types of temperature sensors that can be used are: thermocouples,resistive temperature devices (RTDs and thermistors), IC temperaturesensors etc. Irrespective of the sensor type, an energy source such as abattery or other energy source will be required to provide heat to theshape memory material in order to undergo the phase transformation andcreate a path through the shell. With this system, means must beprovided to connect the shape memory material to the power source andelectrically insulate it to avoid short circuits and energy leaks. Oneadvantage of this system is the ability to have the temperature sensorand the enclosure placed in to two different locations, as long as theyare connected together. The controls (microprocessor, solenoid, switchetc.) can be placed either inside the enclosure or outside. Because, inthis case, the shape memory material is no longer the temperaturesensor, its A_(s) temperature has to be higher than the activationtemperature of the system in order to avoid premature activation. Withan electrically activated system, activation does not have to be due tolocal temperature. Different parameters can be used for activation. Thisenhances the system considerably when it is used as a drug deliverysystem. Sensors can be used to detect parameters such as biologicalactivity and concentrations of different substances and to command theactivation of substance release device once a predetermined parameterhas been exceeded.

In many applications where the drug delivery device is implanted deep inthe body such that direct heating is not applicable, magnetic inductionheating offers an alternative in terms of minimizing the size of thedevice. In this concept, a ferromagnetic material is placed in physicalcontact with the shape memory material. While the ferromagnetic materialis being heated by external magnetic induction, it transfers thermalenergy to the shape memory material and heats it up. Once theferromagnetic material reaches the Curie temperature, it becomesparamagnetic (nonmagnetic) and it stays at this temperature as long asthe external magnetic field is applied. The concept of heating bymagnetic induction is similar to the one used to treat tissue atelevated temperatures by hyperthermia or thermal therapy with thepurpose of destroying cancerous tissue selectively or to necrose allcells. The Curie temperature imposes a self-limit as to how hot thematerial will get before it becomes paramagnetic and loses itsmagnetism. Magnetic induction heated materials are based on alloys suchas; Co—Pd, Ni—Cu, Ni—Pd, Ni—Co, Ni—Si and magnetic stainless steels. Theheating of the magnetic material and consequently of the shape memorymaterial is controlled by the selection of magnetic material with theappropriate Curie temperature.

Physical contact between the magnetic material and the shape memorymaterial can be achieved by methods such as physical interference,filling the space around the shape memory material with the magneticmaterial in a powder form, and coating the shape memory material withthe magnetic material. Issues with biocompatibility of the magneticmaterial do not exist as long as it is placed inside the device and doesnot come in contact with the device's surroundings.

Insulation

To add a time delay at temperature the shape memory material and/or theenclosure can be insulated. The level of insulation will depend on thetime delay desired. This feature will delay the triggering of the deviceuntil thermal equilibrium between the shape memory material and ambientis reached. The delayed trigger will be more representative of theproduct temperature in the case where the device is used for temperaturewarning. Insulation can be in the form of a jacket similar to theinsulation used for electrical wires. Space can be left between thejacket and the shape memory material to be filled with thermallyinsulating material to further delay the shape recovery process. In nocase should the insulation impede the performance of the device.

While the invention has been described in detail with reference to thepreferred embodiments thereof, it will be apparent to one skilled in theart that various changes and modifications can be made and equivalentsemployed, without departing from the present invention.

Deformation

In the description of the preferred embodiments, for optimumperformance, the shape memory material activator is deformed at atemperature in which the material is in the martensitic state. However,certain types of shape memory materials, such as the nickel-titaniumbased alloys, can be deformed at a higher temperature provided that thetemperature at which martensite can be stress-induced is not exceeded.This is known as M_(d) temperature. Generally, strain inducedmartensitic deformation results in permanent strains after shaperecovery and it is not applicable to devices that require temperaturecycling of the shape memory material.

While the invention has been described in detail with reference to thepreferred embodiments thereof, it will be apparent to one skilled in theart that various changes and modifications can be made and equivalentsemployed, without departing from the present invention.

1. A shape memory material activated device for controlling the passingrate of a substance through a shell, the device comprising: a shell; abarrier of variable permeability; and a shape memory material activatorconfigured to create a path through the shell during temperature changessuch that progressive exposure of the variable barrier occurs therebypermitting the substance to pass therethrough at a changing rate.
 2. Thedevice according to claim 1, wherein said barrier forms part of theshell wall.
 3. The device of claim 1, wherein said shape memory materialactivator includes a housing and wherein said path is created throughthe shell by unidirectional volumetric change of the housing caused bythe shape memory material activator undergoing shape cycling duringtemperature changes.
 4. The device according to claim 1, wherein saidbarrier forms part of the shell wall whereby the substance is exuded outunder pressure.
 5. The device according to claim 1, wherein the paththrough the shell includes means for exposing progressively larger pathsduring increasing temperatures.